distr/util/saveimage.c

   1 /* LINTLIBRARY */
   2
   3
   4 /*
   5  * saveimage.c --
   6  *
   7  * Function to save an executable copy of the current process's
   8  * image in a file.
   9  *
  10  */
  11
  12 #include <stdio.h>
  13 #include "util.h"
  14
  15 #ifdef BSD
  16 #include <sys/types.h>
  17 #include <sys/stat.h>
  18 #include <a.out.h>
  19 #include <errno.h>
  20
  21 extern int errno;
  22
  23 #define BUFSIZE         8192
  24
  25 extern long lseek();    /* For lint */
  26 extern int getpagesize();
  27 extern char *sbrk();
  28
  29 static int copy_file();
  30 static int pad_file();
  31
  32
  33 int
  34 util_save_image(char const *orig_file_name, char const *save_file_name)
  35 {
  36     int origFd = -1, saveFd = -1;
  37     char *start_data, *end_data, *start_text, *end_round;
  38     struct exec old_hdr, new_hdr;
  39     struct stat old_stat;
  40     int n, page_size, length_text, length_data;
  41
  42     if ((origFd = open(orig_file_name, 0)) < 0) {
  43         perror(orig_file_name);
  44         (void) fprintf(stderr, "Cannot open original a.out file\n");
  45         goto bad;
  46     }
  47
  48     if (fstat(origFd, &old_stat) < 0) {
  49         perror(orig_file_name);
  50         (void) fprintf(stderr, "Cannot stat original a.out file\n");
  51         goto bad;
  52     }
  53
  54     /*
  55      * Read the a.out header from the original file.
  56      */
  57     if (read(origFd, (char *) &old_hdr, sizeof(old_hdr)) != sizeof(old_hdr)) {
  58         perror(orig_file_name);
  59         (void) fprintf(stderr, "Cannot read original a.out header\n");
  60         goto bad;
  61     }
  62     if (N_BADMAG(old_hdr)) {
  63         (void) fprintf(stderr, "File %s has a bad magic number (%o)\n",
  64                         orig_file_name, old_hdr.a_magic);
  65         goto bad;
  66     }
  67     if (old_hdr.a_magic != ZMAGIC) {
  68         (void) fprintf(stderr, "File %s is not demand-paged\n", orig_file_name);
  69         goto bad;
  70     }
  71
  72     /*
  73      * Open the output file.
  74      */
  75     if (access(save_file_name, /* F_OK */ 0) == 0) {
  76         (void) unlink(save_file_name);
  77     }
  78     if ((saveFd = creat(save_file_name, 0777)) < 0) {
  79         if (errno == ETXTBSY) {
  80             (void) unlink(save_file_name);
  81             saveFd = creat(save_file_name, 0777);
  82         }
  83         if (saveFd < 0) {
  84             perror(save_file_name);
  85             (void) fprintf(stderr, "Cannot create save file.\n");
  86             goto bad;
  87         }
  88     }
  89
  90     /*
  91      * Find out how far the data segment extends.
  92      */
  93     new_hdr = old_hdr;
  94     end_data = sbrk(0);
  95     page_size = getpagesize();
  96     n = ((((int) end_data) + page_size - 1) / page_size) * page_size;
  97     end_round = (char *) n;
  98     if (end_round > end_data) {
  99         end_data = sbrk(end_round - end_data);
 100     }
 101
 102 #ifdef vax
 103     start_text = 0;
 104     length_text = new_hdr.a_text;
 105     start_data = (char *) old_hdr.a_text;
 106     length_data = end_data - start_data;
 107 #endif vax
 108 #ifdef  sun
 109     start_text = (char *) N_TXTADDR(old_hdr) + sizeof(old_hdr);
 110     length_text = old_hdr.a_text - sizeof(old_hdr);
 111     start_data = (char *) N_DATADDR(old_hdr);
 112     length_data = end_data - start_data;
 113 #endif  sun
 114     new_hdr.a_data = end_data - start_data;
 115     new_hdr.a_bss = 0;
 116
 117     /*
 118      * First, the header plus enough pad to extend up to N_TXTOFF.
 119      */
 120     if (write(saveFd, (char *) &new_hdr, (int) sizeof(new_hdr)) !=
 121                                 sizeof(new_hdr)) {
 122         perror("write");
 123         (void) fprintf(stderr, "Error while copying header.\n");
 124         goto bad;
 125     }
 126     if (! pad_file(saveFd, N_TXTOFF(old_hdr) - sizeof(new_hdr))) {
 127         (void) fprintf(stderr, "Error while padding.\n");
 128         goto bad;
 129     }
 130
 131
 132     /*
 133      *  Copy our text segment
 134      */
 135     if (write(saveFd, start_text, length_text) != length_text) {
 136         perror("write");
 137         (void) fprintf(stderr, "Error while copying text segment.\n");
 138         goto bad;
 139     }
 140
 141
 142     /*
 143      *  Copy our data segment
 144      */
 145     if (write(saveFd, start_data, length_data) != length_data) {
 146         perror("write");
 147         (void) fprintf(stderr, "Error while copying data segment.\n");
 148         goto bad;
 149     }
 150
 151     /*
 152      * Copy the symbol table and everything else.
 153      * This takes us to the end of the original file.
 154      */
 155     (void) lseek(origFd, (long) N_SYMOFF(old_hdr), 0);
 156     if (! copy_file(origFd, saveFd, old_stat.st_size - N_SYMOFF(old_hdr))) {
 157         (void) fprintf(stderr, "Error while copying symbol table.\n");
 158         goto bad;
 159     }
 160     (void) close(origFd);
 161     (void) close(saveFd);
 162     return 1;
 163
 164 bad:
 165     if (origFd >= 0) (void) close(origFd);
 166     if (saveFd >= 0) (void) close(saveFd);
 167     return 0;
 168 }
 169
 170
 171 static int
 172 copy_file(inFd, outFd, nbytes)
 173 int inFd, outFd;
 174 unsigned long nbytes;
 175 {
 176     char buf[BUFSIZE];
 177     int nread, ntoread;
 178
 179     while (nbytes > 0) {
 180         ntoread = nbytes;
 181         if (ntoread > sizeof buf) ntoread = sizeof buf;
 182         if ((nread = read(inFd, buf, ntoread)) != ntoread) {
 183             perror("read");
 184             return (0);
 185         }
 186         if (write(outFd, buf, nread) != nread) {
 187             perror("write");
 188             return (0);
 189         }
 190         nbytes -= nread;
 191     }
 192
 193     return (1);
 194 }
 195
 196
 197 static int
 198 pad_file(outFd, nbytes)
 199 int outFd;
 200 int nbytes;
 201 {
 202     char buf[BUFSIZE];
 203     int nzero;
 204
 205     nzero = (nbytes > sizeof(buf)) ? sizeof(buf) : nbytes;
 206     bzero(buf, nzero);
 207     while (nbytes > 0) {
 208         nzero = (nbytes > sizeof(buf)) ? sizeof(buf) : nbytes;
 209         if (write(outFd, buf, nzero) != nzero) {
 210             perror("write");
 211             return (0);
 212         }
 213         nbytes -= nzero;
 214     }
 215
 216     return (1);
 217 }
 218 #else
 219
 220 /* ARGSUSED */
 221 int
 222 util_save_image(char const *orig_file_name, char const *save_file_name)
 223 {
 224     (void) fprintf(stderr,
 225         "util_save_image: not implemented on your operating system\n");
 226     return 0;
 227 }
 228
 229 #endif