mdriver.c

/*
 * mdriver.c - CS:APP Malloc Lab Driver
 * 
 * Uses a collection of trace files to tests a malloc/free/realloc
 * implementation in mm.c.
 *
 * Copyright (c) 2002, R. Bryant and D. O'Hallaron, All rights reserved.
 * May not be used, modified, or copied without permission.
 */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <assert.h>
#include <float.h>
#include <time.h>

#include "mm.h"
#include "memlib.h"
#include "fsecs.h"
#include "config.h"

/**********************
 * Constants and macros
 **********************/

/* Misc */
#define MAXLINE     1024 /* max string size */
#define HDRLINES       4 /* number of header lines in a trace file */
#define LINENUM(i) (i+5) /* cnvt trace request nums to linenums (origin 1) */

/* Returns true if p is ALIGNMENT-byte aligned */
#define IS_ALIGNED(p)  ((((size_t)(p)) % ALIGNMENT) == 0)

/****************************** 
 * The key compound data types 
 *****************************/

/* Records the extent of each block's payload */
typedef struct range_t {
  char *lo;              /* low payload address */
  char *hi;              /* high payload address */
  struct range_t *next;  /* next list element */
} range_t;

/* Characterizes a single trace operation (allocator request) */
typedef struct {
  enum {ALLOC, FREE, REALLOC} type; /* type of request */
  int index;                        /* index for free() to use later */
  int size;                         /* byte size of alloc/realloc request */
} traceop_t;

/* Holds the information for one trace file*/
typedef struct {
  int sugg_heapsize;   /* suggested heap size (unused) */
  int num_ids;         /* number of alloc/realloc ids */
  int num_ops;         /* number of distinct requests */
  int weight;          /* weight for this trace (unused) */
  traceop_t *ops;      /* array of requests */
  char **blocks;       /* array of ptrs returned by malloc/realloc... */
  size_t *block_sizes; /* ... and a corresponding array of payload sizes */
} trace_t;

/* 
 * Holds the params to the xxx_speed functions, which are timed by fcyc. 
 * This struct is necessary because fcyc accepts only a pointer array
 * as input.
 */
typedef struct {
  trace_t *trace;  
  range_t *ranges;
} speed_t;

/* Summarizes the important stats for some malloc function on some trace */
typedef struct {
  /* defined for both libc malloc and student malloc package (mm.c) */
  double ops;      /* number of ops (malloc/free/realloc) in the trace */
  int valid;       /* was the trace processed correctly by the allocator? */
  double secs;     /* number of secs needed to run the trace */

  /* defined only for the student malloc package */
  double util;     /* space utilization for this trace (always 0 for libc) */

  /* Note: secs and util are only defined if valid is true */
} stats_t;

/********************
 * Global variables
 *******************/
int verbose = 0;        /* global flag for verbose output */
static int errors = 0;  /* number of errs found when running student malloc */
char msg[2*MAXLINE];      /* for whenever we need to compose an error message */

/* Directory where default tracefiles are found */
static char tracedir[MAXLINE] = TRACEDIR;

/* The filenames of the default tracefiles */
static char *default_tracefiles[] = {  
  DEFAULT_TRACEFILES, NULL
};


/********************* 
 * Function prototypes 
 *********************/

/* these functions manipulate range lists */
static int add_range(range_t **ranges, char *lo, int size, 
                     int tracenum, int opnum);
static void remove_range(range_t **ranges, char *lo);
static void clear_ranges(range_t **ranges);

/* These functions read, allocate, and free storage for traces */
static trace_t *read_trace(char *tracedir, char *filename);
static void free_trace(trace_t *trace);

/* Routines for evaluating the correctness and speed of libc malloc */
static int eval_libc_valid(trace_t *trace, int tracenum);
static void eval_libc_speed(void *ptr);

/* Routines for evaluating correctnes, space utilization, and speed 
   of the student's malloc package in mm.c */
static int eval_mm_valid(trace_t *trace, int tracenum, range_t **ranges);
static double eval_mm_util(trace_t *trace, int tracenum, range_t **ranges);
static void eval_mm_speed(void *ptr);

/* Various helper routines */
static void printresults(int n, stats_t *stats);
static void usage(void);
static void unix_error(char *msg);
static void malloc_error(int tracenum, int opnum, char *msg);
static void app_error(char *msg);

/**************
 * Main routine
 **************/
int main(int argc, char **argv) {
  int i;
  char c;
  char **tracefiles = NULL;  /* null-terminated array of trace file names */
  int num_tracefiles = 0;    /* the number of traces in that array */
  trace_t *trace = NULL;     /* stores a single trace file in memory */
  range_t *ranges = NULL;    /* keeps track of block extents for one trace */
  stats_t *libc_stats = NULL;/* libc stats for each trace */
  stats_t *mm_stats = NULL;  /* mm (i.e. student) stats for each trace */
  speed_t speed_params;      /* input parameters to the xx_speed routines */ 

  /* int team_check = 0; */        /* If set, check team structure (reset by -a) */
  int run_libc = 0;          /* If set, run libc malloc (set by -l) */
  int autograder = 0;        /* If set, emit summary info for autograder (-g) */

  /* temporaries used to compute the performance index */
  double secs, ops, util, avg_mm_util, avg_mm_throughput, p1, p2, perfindex;
  int numcorrect;
    
  /* 
   * Read and interpret the command line arguments 
   */
  while ((c = getopt(argc, argv, "f:t:hvVgal")) != EOF) {
    switch (c) {
      case 'g': /* Generate summary info for the autograder */
        autograder = 1;
        break;
      case 'f': /* Use one specific trace file only (relative to curr dir) */
        num_tracefiles = 1;
        if ((tracefiles = realloc(tracefiles, 2*sizeof(char *))) == NULL)
          unix_error("ERROR: realloc failed in main");
        strcpy(tracedir, "./"); 
        tracefiles[0] = strdup(optarg);
        tracefiles[1] = NULL;
        break;
      case 't': /* Directory where the traces are located */
        if (num_tracefiles == 1) /* ignore if -f already encountered */
          break;
        strcpy(tracedir, optarg);
        if (tracedir[strlen(tracedir)-1] != '/') 
          strcat(tracedir, "/"); /* path always ends with "/" */
        break;
      case 'a': /* Don't check team structure */
        /* team_check = 0; */
        break;
      case 'l': /* Run libc malloc */
        run_libc = 1;
        break;
      case 'v': /* Print per-trace performance breakdown */
        verbose = 1;
        break;
      case 'V': /* Be more verbose than -v */
        verbose = 2;
        break;
      case 'h': /* Print this message */
        usage();
        exit(0);
      default:
        usage();
        exit(1);
    }
  }

  /* 
   * If no -f command line arg, then use the entire set of tracefiles 
   * defined in default_traces[]
   */
  if (tracefiles == NULL) {
    tracefiles = default_tracefiles;
    num_tracefiles = sizeof(default_tracefiles) / sizeof(char *) - 1;
    printf("Using default tracefiles in %s\n", tracedir);
  }

  /* Initialize the timing package */
  init_fsecs();

  /*
   * Optionally run and evaluate the libc malloc package 
   */
  if (run_libc) {
    if (verbose > 1)
      printf("\nTesting libc malloc\n");
  
    /* Allocate libc stats array, with one stats_t struct per tracefile */
    libc_stats = (stats_t *)calloc(num_tracefiles, sizeof(stats_t));
    if (libc_stats == NULL)
      unix_error("libc_stats calloc in main failed");
    
    /* Evaluate the libc malloc package */
    for (i=0; i < num_tracefiles; i++) {
      trace = read_trace(tracedir, tracefiles[i]);
      libc_stats[i].ops = trace->num_ops;
      if (verbose > 1)
        printf("Checking libc malloc for correctness, ");
      libc_stats[i].valid = eval_libc_valid(trace, i);
      if (libc_stats[i].valid) {
        speed_params.trace = trace;
        if (verbose > 1)
          printf("and performance.\n");
        libc_stats[i].secs = fsecs(eval_libc_speed, &speed_params);
      }
      free_trace(trace);
    }

    /* Display the libc results in a compact table */
    if (verbose) {
      printf("\nResults for libc malloc:\n");
      printresults(num_tracefiles, libc_stats);
    }
  }

  /*
   * Always run and evaluate the student's mm package
   */
  if (verbose > 1)
    printf("\nTesting mm_malloc\n");

  /* Allocate the mm stats array, with one stats_t struct per tracefile */
  mm_stats = (stats_t *)calloc(num_tracefiles, sizeof(stats_t));
  if (mm_stats == NULL)
    unix_error("mm_stats calloc in main failed");
  
  /* Initialize the simulated memory system in memlib.c */
  mem_init(); 

  /* Evaluate student's mm malloc package */
  for (i=0; i < num_tracefiles; i++) {
    trace = read_trace(tracedir, tracefiles[i]);
    mm_stats[i].ops = trace->num_ops;
    if (verbose > 1)
      printf("Checking mm_malloc for correctness, ");
    mm_stats[i].valid = eval_mm_valid(trace, i, &ranges);
    if (mm_stats[i].valid) {
      if (verbose > 1)
        printf("efficiency, ");
      mm_stats[i].util = eval_mm_util(trace, i, &ranges);
      speed_params.trace = trace;
      speed_params.ranges = ranges;
      if (verbose > 1)
        printf("and performance.\n");
      mm_stats[i].secs = fsecs(eval_mm_speed, &speed_params);
    }
    free_trace(trace);
  }

    /* Display the mm results in a compact table */
  if (verbose) {
    printf("\nResults for mm_malloc:\n");
    printresults(num_tracefiles, mm_stats);
    printf("\n");
  }

  /* 
   * Accumulate the aggregate statistics for the student's mm package 
   */
  secs = 0;
  ops = 0;
  util = 0;
  numcorrect = 0;
  for (i=0; i < num_tracefiles; i++) {
    secs += mm_stats[i].secs;
    ops += mm_stats[i].ops;
    util += mm_stats[i].util;
    if (mm_stats[i].valid)
      numcorrect++;
  }
  avg_mm_util = util/num_tracefiles;

  /* 
   * Compute and print the performance index 
   */
  if (errors == 0) {
    avg_mm_throughput = ops/secs;

    p1 = UTIL_WEIGHT * avg_mm_util;
    if (avg_mm_throughput > AVG_LIBC_THRUPUT) {
      p2 = (double)(1.0 - UTIL_WEIGHT);
    } 
    else {
      p2 = ((double) (1.0 - UTIL_WEIGHT)) * (avg_mm_throughput/AVG_LIBC_THRUPUT);
    }
    
    perfindex = (p1 + p2)*100.0;
    printf("Perf index = %.0f (util) + %.0f (thru) = %.0f/100\n",
           p1*100, p2*100, perfindex);
  }
  else { /* There were errors */
    perfindex = 0.0;
    printf("Terminated with %d errors\n", errors);
  }

  if (autograder) {
    printf("correct: %d\n", numcorrect);
    printf("perfidx: %.0f\n", perfindex);
  }

  exit(0);
}


/*****************************************************************
 * The following routines manipulate the range list, which keeps 
 * track of the extent of every allocated block payload. We use the 
 * range list to detect any overlapping allocated blocks.
 ****************************************************************/

/*
 * add_range - As directed by request opnum in trace tracenum,
 *   we've just called the student's mm_malloc to allocate a block of 
 *   size bytes at addr lo. After checking the block for correctness,
 *   we create a range struct for this block and add it to the range list. 
 */
static int add_range(range_t **ranges, char *lo, int size, 
                     int tracenum, int opnum) {
  char *hi = lo + size - 1;
  range_t *p;
  char msg[MAXLINE];

  assert(size > 0);

  /* Payload addresses must be ALIGNMENT-byte aligned */
  if (!IS_ALIGNED(lo)) {
    sprintf(msg, "Payload address (%p) not aligned to %d bytes",
            lo, ALIGNMENT);
    malloc_error(tracenum, opnum, msg);
    return 0;
  }

  /* The payload must lie within the extent of the heap */
  if ((lo < (char *)mem_heap_lo()) || (lo > (char *)mem_heap_hi()) || 
      (hi < (char *)mem_heap_lo()) || (hi > (char *)mem_heap_hi())) {
    sprintf(msg, "Payload (%p:%p) lies outside heap (%p:%p)",
            lo, hi, mem_heap_lo(), mem_heap_hi());
    malloc_error(tracenum, opnum, msg);
    return 0;
  }

  /* The payload must not overlap any other payloads */
  for (p = *ranges;  p != NULL;  p = p->next) {
    if ((lo >= p->lo && lo <= p->hi) || (hi >= p->lo && hi <= p->hi)) {
      sprintf(msg, "Payload (%p:%p) overlaps another payload (%p:%p)\n",
              lo, hi, p->lo, p->hi);
      malloc_error(tracenum, opnum, msg);
      return 0;
    }
  }

  /* 
   * Everything looks OK, so remember the extent of this block 
   * by creating a range struct and adding it the range list.
   */
  if ((p = (range_t *)malloc(sizeof(range_t))) == NULL)
    unix_error("malloc error in add_range");
  p->next = *ranges;
  p->lo = lo;
  p->hi = hi;
  *ranges = p;
  return 1;
}

/* 
 * remove_range - Free the range record of block whose payload starts at lo 
 */
static void remove_range(range_t **ranges, char *lo) {
  range_t *p;
  range_t **prevpp = ranges;

  for (p = *ranges; p != NULL; p = p->next) {
    if (p->lo == lo) {
      *prevpp = p->next;
      free(p);
      break;
    }
    prevpp = &(p->next);
  }
}

/*
 * clear_ranges - free all of the range records for a trace 
 */
static void clear_ranges(range_t **ranges) {
  range_t *p;
  range_t *pnext;

  for (p = *ranges; p != NULL; p = pnext) {
    pnext = p->next;
    free(p);
  }
  *ranges = NULL;
}


/**********************************************
 * The following routines manipulate tracefiles
 *********************************************/

/*
 * read_trace - read a trace file and store it in memory
 */
static trace_t *read_trace(char *tracedir, char *filename) {
  FILE *tracefile;
  trace_t *trace;
  char type[MAXLINE];
  char path[MAXLINE];
  unsigned int index, size;
  unsigned int max_index = 0;
  unsigned int op_index;
  int ret_val = 0;

  if (verbose > 1)
    printf("Reading tracefile: %s\n", filename);

  /* Allocate the trace record */
  if ((trace = (trace_t *)malloc(sizeof(trace_t))) == NULL)
    unix_error("malloc 1 failed in read_trace");
  
  /* Read the trace file header */
  strcpy(path, tracedir);
  strcat(path, filename);
  if ((tracefile = fopen(path, "r")) == NULL) {
    sprintf(msg, "Could not open %s in read_trace", path);
    unix_error(msg);
  }
  ret_val = fscanf(tracefile, "%d", &(trace->sugg_heapsize)); /* not used */
  if (ret_val != 1) app_error("fscanf error 1 in read_trace");
  ret_val = fscanf(tracefile, "%d", &(trace->num_ids));
  if (ret_val != 1) app_error("fscanf error 2 in read_trace");
  ret_val = fscanf(tracefile, "%d", &(trace->num_ops));
  if (ret_val != 1) app_error("fscanf error 3 in read_trace");
  ret_val = fscanf(tracefile, "%d", &(trace->weight));        /* not used */
  if (ret_val != 1) app_error("fscanf error 4 in read_trace");
    
  /* We'll store each request line in the trace in this array */
  trace->ops = (traceop_t *)malloc(trace->num_ops * sizeof(traceop_t));
  if (trace->ops == NULL)
    unix_error("malloc 2 failed in read_trace");

  /* We'll keep an array of pointers to the allocated blocks here... */
  trace->blocks = (char **)malloc(trace->num_ids * sizeof(char *));
  if (trace->blocks == NULL)
    unix_error("malloc 3 failed in read_trace");

  /* ... along with the corresponding byte sizes of each block */
  trace->block_sizes = (size_t *)malloc(trace->num_ids * sizeof(size_t));
  if (trace->block_sizes == NULL)
    unix_error("malloc 4 failed in read_trace");
    
  /* read every request line in the trace file */
  index = 0;
  op_index = 0;
  while (fscanf(tracefile, "%s", type) != EOF) {
    switch(type[0]) {
      case 'a':
        ret_val = fscanf(tracefile, "%u %u", &index, &size);
        if (ret_val != 2) app_error("fscanf error 5 in read_trace");
        trace->ops[op_index].type = ALLOC;
        trace->ops[op_index].index = index;
        trace->ops[op_index].size = size;
        max_index = (index > max_index) ? index : max_index;
        break;
      case 'r':
        ret_val = fscanf(tracefile, "%u %u", &index, &size);
        if (ret_val != 2) app_error("fscanf error 6 in read_trace");
        trace->ops[op_index].type = REALLOC;
        trace->ops[op_index].index = index;
        trace->ops[op_index].size = size;
        max_index = (index > max_index) ? index : max_index;
        break;
      case 'f':
        ret_val = fscanf(tracefile, "%ud", &index);
        if (ret_val != 1) app_error("fscanf error 7 in read_trace");
        trace->ops[op_index].type = FREE;
        trace->ops[op_index].index = index;
        break;
      default:
        printf("Bogus type character (%c) in tracefile %s\n", type[0], path);
        exit(1);
    }
    op_index++;
  }
  fclose(tracefile);
  assert(max_index == trace->num_ids - 1);
  assert(trace->num_ops == op_index);
    
  return trace;
}

/*
 * free_trace - Free the trace record and the three arrays it points
 *   to, all of which were allocated in read_trace().
 */
void free_trace(trace_t *trace) {
  free(trace->ops);         /* free the three arrays... */
  free(trace->blocks);      
  free(trace->block_sizes);
  free(trace);              /* and the trace record itself... */
}

/**********************************************************************
 * The following functions evaluate the correctness, space utilization,
 * and throughput of the libc and mm malloc packages.
 **********************************************************************/

/*
 * eval_mm_valid - Check the mm malloc package for correctness
 */
static int eval_mm_valid(trace_t *trace, int tracenum, range_t **ranges) {
  int i, j;
  int index;
  int size;
  int oldsize;
  char *newp;
  char *oldp;
  char *p;
    
  /* Reset the heap and free any records in the range list */
  mem_reset_brk();
  clear_ranges(ranges);

  /* Call the mm package's init function */
  if (mm_init() < 0) {
    malloc_error(tracenum, 0, "mm_init failed.");
    return 0;
  }

  /* Interpret each operation in the trace in order */
  for (i = 0; i < trace->num_ops; i++) {
    index = trace->ops[i].index;
    size = trace->ops[i].size;

    switch (trace->ops[i].type) {
      case ALLOC: /* mm_malloc */
        /* Call the student's malloc */
        if ((p = mm_malloc(size)) == NULL) {
          malloc_error(tracenum, i, "mm_malloc failed.");
          return 0;
        }
      
        /* 
         * Test the range of the new block for correctness and add it 
         * to the range list if OK. The block must be be aligned properly,
         * and must not overlap any currently allocated block. 
         */ 
        if (add_range(ranges, p, size, tracenum, i) == 0)
          return 0;
      
        /* ADDED: cgw
         * fill range with low byte of index.  This will be used later
         * if we realloc the block and wish to make sure that the old
         * data was copied to the new block
         */
        memset(p, index & 0xFF, size);

        /* Remember region */
        trace->blocks[index] = p;
        trace->block_sizes[index] = size;
        break;

      case REALLOC: /* mm_realloc */
        /* Call the student's realloc */
        oldp = trace->blocks[index];
        if ((newp = mm_realloc(oldp, size)) == NULL) {
          malloc_error(tracenum, i, "mm_realloc failed.");
          return 0;
        }
      
        /* Remove the old region from the range list */
        remove_range(ranges, oldp);
      
        /* Check new block for correctness and add it to range list */
        if (add_range(ranges, newp, size, tracenum, i) == 0)
          return 0;
      
        /* ADDED: cgw
         * Make sure that the new block contains the data from the old 
         * block and then fill in the new block with the low order byte
         * of the new index
         */
        oldsize = trace->block_sizes[index];
        if (size < oldsize) oldsize = size;
        for (j = 0; j < oldsize; j++) {
          if (newp[j] != (index & 0xFF)) {
            malloc_error(tracenum, i, "mm_realloc did not preserve the "
                         "data from old block");
            return 0;
          }
        }
        memset(newp, index & 0xFF, size);

        /* Remember region */
        trace->blocks[index] = newp;
        trace->block_sizes[index] = size;
        break;

      case FREE: /* mm_free */
        /* Remove region from list and call student's free function */
        p = trace->blocks[index];
        remove_range(ranges, p);
        mm_free(p);
        break;

      default:
        app_error("Nonexistent request type in eval_mm_valid");
    }
  }

  /* As far as we know, this is a valid malloc package */
  return 1;
}

/* 
 * eval_mm_util - Evaluate the space utilization of the student's package
 *   The idea is to remember the high water mark "hwm" of the heap for 
 *   an optimal allocator, i.e., no gaps and no internal fragmentation.
 *   Utilization is the ratio hwm/heapsize, where heapsize is the 
 *   size of the heap in bytes after running the student's malloc 
 *   package on the trace. Note that our implementation of mem_sbrk() 
 *   doesn't allow the students to decrement the brk pointer, so brk
 *   is always the high water mark of the heap. 
 */
static double eval_mm_util(trace_t *trace, int tracenum, range_t **ranges) {   
  int i;
  int index;
  int size, newsize, oldsize;
  int max_total_size = 0;
  int total_size = 0;
  char *p;
  char *newp, *oldp;

  /* initialize the heap and the mm malloc package */
  mem_reset_brk();
  if (mm_init() < 0)
    app_error("mm_init failed in eval_mm_util");

  for (i = 0; i < trace->num_ops; i++) {
    switch (trace->ops[i].type) {
      case ALLOC: /* mm_alloc */
        index = trace->ops[i].index;
        size = trace->ops[i].size;

        if ((p = mm_malloc(size)) == NULL) 
          app_error("mm_malloc failed in eval_mm_util");
    
        /* Remember region and size */
        trace->blocks[index] = p;
        trace->block_sizes[index] = size;
    
        /* Keep track of current total size
          * of all allocated blocks */
        total_size += size;
    
        /* Update statistics */
        max_total_size = (total_size > max_total_size)
                       ? total_size : max_total_size;
        break;

      case REALLOC: /* mm_realloc */
        index = trace->ops[i].index;
        newsize = trace->ops[i].size;
        oldsize = trace->block_sizes[index];

        oldp = trace->blocks[index];
        if ((newp = mm_realloc(oldp,newsize)) == NULL)
          app_error("mm_realloc failed in eval_mm_util");

        /* Remember region and size */
        trace->blocks[index] = newp;
        trace->block_sizes[index] = newsize;
    
        /* Keep track of current total size
          * of all allocated blocks */
        total_size += (newsize - oldsize);
    
        /* Update statistics */
        max_total_size = (total_size > max_total_size)
                       ? total_size : max_total_size;
        break;

      case FREE: /* mm_free */
        index = trace->ops[i].index;
        size = trace->block_sizes[index];
        p = trace->blocks[index];
    
        mm_free(p);
    
        /* Keep track of current total size
          * of all allocated blocks */
        total_size -= size;
    
        break;

      default:
        app_error("Nonexistent request type in eval_mm_util");
    }
  }
  return ((double)max_total_size / (double)mem_heapsize());
}


/*
 * eval_mm_speed - This is the function that is used by fsecs()
 *   to measure the running time of the mm malloc package.
 */
static void eval_mm_speed(void *ptr) {
  int i, index, size, newsize;
  char *p, *newp, *oldp, *block;
  trace_t *trace = ((speed_t *)ptr)->trace;

  /* Reset the heap and initialize the mm package */
  mem_reset_brk();
  if (mm_init() < 0) 
    app_error("mm_init failed in eval_mm_speed");

  /* Interpret each trace request */
  for (i = 0; i < trace->num_ops; i++)
    switch (trace->ops[i].type) {
      case ALLOC: /* mm_malloc */
        index = trace->ops[i].index;
        size = trace->ops[i].size;
        if ((p = mm_malloc(size)) == NULL)
          app_error("mm_malloc error in eval_mm_speed");
        trace->blocks[index] = p;
        break;

      case REALLOC: /* mm_realloc */
        index = trace->ops[i].index;
        newsize = trace->ops[i].size;
        oldp = trace->blocks[index];
        if ((newp = mm_realloc(oldp,newsize)) == NULL)
          app_error("mm_realloc error in eval_mm_speed");
        trace->blocks[index] = newp;
        break;

      case FREE: /* mm_free */
        index = trace->ops[i].index;
        block = trace->blocks[index];
        mm_free(block);
        break;

      default:
        app_error("Nonexistent request type in eval_mm_valid");
    }
}

/*
 * eval_libc_valid - We run this function to make sure that the
 *   libc malloc can run to completion on the set of traces.
 *   We'll be conservative and terminate if any libc malloc call fails.
 */
static int eval_libc_valid(trace_t *trace, int tracenum) {
  int i, newsize;
  char *p, *newp, *oldp;

  for (i = 0; i < trace->num_ops; i++) {
    switch (trace->ops[i].type) {
      case ALLOC: /* malloc */
        if ((p = malloc(trace->ops[i].size)) == NULL) {
          malloc_error(tracenum, i, "libc malloc failed");
          unix_error("System message");
        }
        trace->blocks[trace->ops[i].index] = p;
        break;
      case REALLOC: /* realloc */
        newsize = trace->ops[i].size;
        oldp = trace->blocks[trace->ops[i].index];
        if ((newp = realloc(oldp, newsize)) == NULL) {
          malloc_error(tracenum, i, "libc realloc failed");
          unix_error("System message");
        }
        trace->blocks[trace->ops[i].index] = newp;
        break;
      case FREE: /* free */
        free(trace->blocks[trace->ops[i].index]);
        break;
      default:
        app_error("invalid operation type in eval_libc_valid");
    }
  }

  return 1;
}

/* 
 * eval_libc_speed - This is the function that is used by fsecs() to
 *   measure the running time of the libc malloc package on the set
 *   of traces.
 */
static void eval_libc_speed(void *ptr) {
  int i;
  int index, size, newsize;
  char *p, *newp, *oldp, *block;
  trace_t *trace = ((speed_t *)ptr)->trace;

  for (i = 0;  i < trace->num_ops;  i++) {
    switch (trace->ops[i].type) {
      case ALLOC: /* malloc */
        index = trace->ops[i].index;
        size = trace->ops[i].size;
        if ((p = malloc(size)) == NULL)
          unix_error("malloc failed in eval_libc_speed");
        trace->blocks[index] = p;
        break;
      case REALLOC: /* realloc */
        index = trace->ops[i].index;
        newsize = trace->ops[i].size;
        oldp = trace->blocks[index];
        if ((newp = realloc(oldp, newsize)) == NULL)
          unix_error("realloc failed in eval_libc_speed\n");
        trace->blocks[index] = newp;
        break;
      case FREE: /* free */
        index = trace->ops[i].index;
        block = trace->blocks[index];
        free(block);
        break;
    }
  }
}

/*************************************
 * Some miscellaneous helper routines
 ************************************/

/*
 * printresults - prints a performance summary for some malloc package
 */
static void printresults(int n, stats_t *stats) {
  int i;
  double secs = 0;
  double ops = 0;
  double util = 0;

  /* Print the individual results for each trace */
  printf("%5s%7s %5s%8s%10s%6s\n", 
    "trace", " valid", "util", "ops", "secs", "Kops");
  for (i=0; i < n; i++) {
    if (stats[i].valid) {
      printf("%2d%10s%5.0f%%%8.0f%10.7f %6.0f\n", 
             i,
             "yes",
             stats[i].util*100.0,
             stats[i].ops,
             stats[i].secs,
             (stats[i].ops/1e3)/stats[i].secs);
      secs += stats[i].secs;
      ops += stats[i].ops;
      util += stats[i].util;
    }
    else {
      printf("%2d%10s%6s%8s%10s %6s\n", 
             i,
             "no",
             "-",
             "-",
             "-",
             "-");
    }
  }

  /* Print the aggregate results for the set of traces */
  if (errors == 0) {
    printf("%12s%5.0f%%%8.0f%10.7f %6.0f\n", 
           "Total       ",
           (util/n)*100.0,
           ops, 
           secs,
           (ops/1e3)/secs);
  }
  else {
    printf("%12s%6s%8s%10s %6s\n", 
           "Total       ",
           "-", 
           "-", 
           "-", 
           "-");
  }
}

/* 
 * app_error - Report an arbitrary application error
 */
void app_error(char *msg) {
  printf("%s\n", msg);
  exit(1);
}

/* 
 * unix_error - Report a Unix-style error
 */
void unix_error(char *msg) {
  printf("%s: %s\n", msg, strerror(errno));
  exit(1);
}

/*
 * malloc_error - Report an error returned by the mm_malloc package
 */
void malloc_error(int tracenum, int opnum, char *msg) {
  errors++;
  printf("ERROR [trace %d, line %d]: %s\n", tracenum, LINENUM(opnum), msg);
}

/* 
 * usage - Explain the command line arguments
 */
static void usage(void) {
  fprintf(stderr, "Usage: mdriver [-hvVal] [-f <file>] [-t <dir>]\n");
  fprintf(stderr, "Options\n");
  fprintf(stderr, "\t-a         Don't check the team structure.\n");
  fprintf(stderr, "\t-f <file>  Use <file> as the trace file.\n");
  fprintf(stderr, "\t-g         Generate summary info for autograder.\n");
  fprintf(stderr, "\t-h         Print this message.\n");
  fprintf(stderr, "\t-l         Run libc malloc as well.\n");
  fprintf(stderr, "\t-t <dir>   Directory to find default traces.\n");
  fprintf(stderr, "\t-v         Print per-trace performance breakdowns.\n");
  fprintf(stderr, "\t-V         Print additional debug info.\n");
}