Beginnings of a crude utility to dump the contents of an OMF file

Beginnings of a crude utility to dump the contents of an OMF (obj)
file.  At this point all it does it breaks it down into the individual
records and dumps those, but it is still easier to read than a pure
hexdump.

See http://www.azillionmonkeys.com/qed/Omfg.pdf for the format spec.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

diff --git a/misc/omfdump.c b/misc/omfdump.c
new file mode 100644 (file)
index 0000000..322971e
--- /dev/null
+++ b/misc/omfdump.c
@@ -0,0 +1,223 @@
+/*
+ * omfdump.c
+ *
+ * Very simple program to dump the contents of an OMF (OBJ) file
+ *
+ * This assumes a littleendian, unaligned-load-capable host and a
+ * C compiler which handles basic C99.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <inttypes.h>
+#include <ctype.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+
+const char *progname;
+
+static const char *record_types[256] =
+{
+    [0x80] = "THEADR",
+    [0x82] = "LHEADR",
+    [0x88] = "COMENT",
+    [0x8a] = "MODEND16",
+    [0x8b] = "MODEND32",
+    [0x8c] = "EXTDEF",
+    [0x90] = "PUBDEF16",
+    [0x91] = "PUBDEF32",
+    [0x94] = "LINNUM16",
+    [0x95] = "LINNUM32",
+    [0x96] = "LNAMES",
+    [0x98] = "SEGDEF16",
+    [0x99] = "SEGDEF32",
+    [0x9a] = "GRPDEF",
+    [0x9c] = "FIXUPP16",
+    [0x9d] = "FIXUPP32",
+    [0xa0] = "LEDATA16",
+    [0xa1] = "LEDATA32",
+    [0xa2] = "LIDATA16",
+    [0xa3] = "LIDATA32",
+    [0xb0] = "COMDEF",
+    [0xb2] = "BAKPAT16",
+    [0xb3] = "BAKPAT32",
+    [0xb4] = "LEXTDEF",
+    [0xb6] = "LPUBDEF16",
+    [0xb7] = "LPUBDEF32",
+    [0xb8] = "LCOMDEF",
+    [0xbc] = "CEXTDEF",
+    [0xc2] = "COMDAT16",
+    [0xc3] = "COMDAT32",
+    [0xc4] = "LINSYM16",
+    [0xc5] = "LINSYM32",
+    [0xc6] = "ALIAS",
+    [0xc8] = "NBKPAT16",
+    [0xc9] = "NBKPAT32",
+    [0xca] = "LLNAMES",
+    [0xcc] = "VERNUM",
+    [0xce] = "VENDEXT",
+    [0xf0] = "LIBHDR",
+    [0xf1] = "LIBEND",
+};
+
+typedef void (*dump_func)(uint8_t, const uint8_t *, size_t);
+
+static void hexdump_data(unsigned int offset, const uint8_t *data, size_t n)
+{
+    unsigned int i, j;
+
+    for (i = 0; i < n; i += 16) {
+       printf("  %04x: ", i+offset);
+       for (j = 0; j < 16; j++) {
+           if (i+j < n)
+               printf("%02x%c", data[i+j], (j == 7) ? '-' : ' ');
+           else
+               printf("   ");
+       }
+       printf(" :  ");
+       for (j = 0; j < 16; j++) {
+           if (i+j < n)
+               putchar(isprint(data[i+j]) ? data[i+j] : '.');
+       }
+       putchar('\n');
+    }
+}
+
+static void dump_unknown(uint8_t type, const uint8_t *data, size_t n)
+{
+    (void)type;
+    hexdump_data(0, data, n);
+}
+
+static void dump_coment(uint8_t type, const uint8_t *data, size_t n)
+{
+    uint8_t class;
+    static const char *coment_class[256] = {
+       [0x00] = "Translator",
+       [0x01] = "Copyright",
+       [0x81] = "Library specifier",
+       [0x9c] = "MS-DOS version",
+       [0x9d] = "Memory model",
+       [0x9e] = "DOSSEG",
+       [0x9f] = "Library search",
+       [0xa0] = "OMF extensions",
+       [0xa1] = "New OMF extension",
+       [0xa2] = "Link pass separator",
+       [0xa3] = "LIBMOD",
+       [0xa4] = "EXESTR",
+       [0xa6] = "INCERR",
+       [0xa7] = "NOPAD",
+       [0xa8] = "WKEXT",
+       [0xa9] = "LZEXT",
+       [0xda] = "Comment",
+       [0xdb] = "Compiler",
+       [0xdc] = "Date",
+       [0xdd] = "Timestamp",
+       [0xdf] = "User",
+       [0xe9] = "Dependency file",
+       [0xff] = "Command line"
+    };
+
+    if (n < 2) {
+       dump_unknown(type, data, n);
+       return;
+    }
+
+    type  = data[0];
+    class = data[1];
+
+    printf("  [NP=%d NL=%d UD=%02X] %02X %s\n",
+          (type >> 7) & 1,
+          (type >> 6) & 1,
+          type & 0x3f,
+          class,
+          coment_class[class] ? coment_class[class] : "???");
+
+    hexdump_data(2, data+2, n-2);
+}
+
+static const dump_func dump_type[256] =
+{
+    [0x88] = dump_coment,
+};
+
+int dump_omf(int fd)
+{
+    struct stat st;
+    size_t len, n;
+    uint8_t type;
+    const uint8_t *p, *data;
+
+    if (fstat(fd, &st))
+       return -1;
+
+    len = st.st_size;
+
+    data = mmap(NULL, len, PROT_READ, MAP_PRIVATE, fd, 0);
+    if (data == MAP_FAILED)
+       return -1;
+
+    p = data;
+    while (len >= 3) {
+       uint8_t csum;
+       int i;
+
+       type = p[0];
+       n = *(uint16_t *)(p+1);
+
+       printf("%02x %-10s %4zd bytes",
+              type,
+              record_types[type] ? record_types[type] : "???",
+              n);
+
+       if (len < n+3) {
+           printf("\n  (truncated, only %zd bytes left)\n", len-3);
+           break;              /* Truncated */
+       }
+
+       p += 3;       /* Header doesn't count in the length */
+       n--;          /* Remove checksum byte */
+
+       csum = 0;
+       for (i = -3; i < (int)n; i++)
+           csum -= p[i];
+
+       printf(", checksum %02X", p[i]);
+       if (csum == p[i])
+           printf(" (valid)\n");
+       else
+           printf(" (actual = %02X)\n", csum);
+
+       if (dump_type[type])
+           dump_type[type](type, p, n);
+       else
+           dump_unknown(type, p, n);
+
+       p   += n+1;
+       len -= (n+4);
+    }
+
+    munmap((void *)data, st.st_size);
+    return 0;
+}
+
+int main(int argc, char *argv[])
+{
+    int fd;
+    int i;
+
+    progname = argv[0];
+
+    for (i = 1; i < argc; i++) {
+       fd = open(argv[i], O_RDONLY);
+       if (fd < 0 || dump_omf(fd)) {
+           perror(argv[i]);
+           return 1;
+       }
+       close(fd);
+    }
+
+    return 0;
+}