symtab loader

diff --git a/cmpmrg_text.c b/cmpmrg_text.c
index ea7223c..a7191b3 100644 (file)
--- a/cmpmrg_text.c
+++ b/cmpmrg_text.c
@@ -47,6 +47,29 @@ typedef struct {
   unsigned short r_type;    /* type of relocation         */
 } __attribute__((packed)) RELOC;
 
+typedef struct {
+  union {
+    char e_name[E_SYMNMLEN];
+    struct {
+      unsigned int e_zeroes;
+      unsigned int e_offset;
+    } e;
+  } e;
+  unsigned int e_value;
+  short e_scnum;
+  unsigned short e_type;
+  unsigned char e_sclass;
+  unsigned char e_numaux;
+} __attribute__((packed)) SYMENT;
+
+#define C_EXT 2
+
+struct my_symtab {
+  unsigned int addr;
+  unsigned int fpos; // for patching
+  char *name;
+};
+
 static void my_assert_(int line, const char *name, long v, long expect, int is_eq)
 {
        int ok;
@@ -67,19 +90,40 @@ static void my_assert_(int line, const char *name, long v, long expect, int is_e
 #define my_assert_not(v, exp) \
        my_assert_(__LINE__, #v, (long)(v), (long)(exp), 0)
 
+static int symt_cmp(const void *p1_, const void *p2_)
+{
+       const struct my_symtab *p1 = p1_, *p2 = p2_;
+       return p1->addr - p2->addr;
+}
+
 void parse_headers(FILE *f, unsigned int *base_out,
        long *sect_ofs, uint8_t **sect_data, long *sect_sz,
-       RELOC **relocs, long *reloc_cnt)
+       RELOC **relocs, long *reloc_cnt,
+       struct my_symtab **symtab_out, long *sym_cnt)
 {
+       struct my_symtab *symt_o = NULL;
+       char *stringtab = NULL;
        unsigned int base = 0;
+       int text_scnum = 0;
+       long filesize;
+       char symname[9];
        long opthdr_pos;
        long reloc_size;
        FILHDR hdr;
        AOUTHDR opthdr;
        SCNHDR scnhdr;
-       int s, val;
+       SYMENT syment;
+       int i, s, val;
        int ret;
        
+       ret = fseek(f, 0, SEEK_END);
+       my_assert(ret, 0);
+
+       filesize = ftell(f);
+
+       ret = fseek(f, 0, SEEK_SET);
+       my_assert(ret, 0);
+
        ret = fread(&hdr, 1, sizeof(hdr), f);
        my_assert(ret, sizeof(hdr));
 
@@ -125,18 +169,22 @@ void parse_headers(FILE *f, unsigned int *base_out,
                my_assert(ret, 0);
        }
 
+       // note: assuming first non-empty one is .text ..
        for (s = 0; s < hdr.f_nscns; s++) {
                ret = fread(&scnhdr, 1, sizeof(scnhdr), f);
                my_assert(ret, sizeof(scnhdr));
 
-               if (scnhdr.s_size != 0)
+               if (scnhdr.s_size != 0) {
+                       text_scnum = s + 1;
                        break;
+               }
        }
 
+       printf("f_nsyms:  %x\n", hdr.f_nsyms);
        printf("s_name:   '%s'\n", scnhdr.s_name);
        printf("s_vaddr:  %x\n", scnhdr.s_vaddr);
        printf("s_size:   %x\n", scnhdr.s_size);
-       printf("s_scnptr: %x\n", scnhdr.s_scnptr);
+       //printf("s_scnptr: %x\n", scnhdr.s_scnptr);
        printf("s_nreloc: %x\n", scnhdr.s_nreloc);
        printf("--\n");
 
@@ -151,6 +199,7 @@ void parse_headers(FILE *f, unsigned int *base_out,
        *sect_ofs = scnhdr.s_scnptr;
        *sect_sz = scnhdr.s_size;
 
+       // relocs
        ret = fseek(f, scnhdr.s_relptr, SEEK_SET);
        my_assert(ret, 0);
 
@@ -162,7 +211,66 @@ void parse_headers(FILE *f, unsigned int *base_out,
 
        *reloc_cnt = scnhdr.s_nreloc;
 
-       if (base != 0)
+       // symtab
+       if (hdr.f_nsyms != 0) {
+               symname[8] = 0;
+
+               symt_o = malloc(hdr.f_nsyms * sizeof(symt_o[0]) + 1);
+               my_assert_not(symt_o, NULL);
+
+               ret = fseek(f, hdr.f_symptr
+                               + hdr.f_nsyms * sizeof(syment), SEEK_SET);
+               my_assert(ret, 0);
+               ret = fread(&i, 1, sizeof(i), f);
+               my_assert(ret, sizeof(i));
+               my_assert((unsigned int)i < filesize, 1);
+
+               stringtab = malloc(i);
+               my_assert_not(stringtab, NULL);
+               memset(stringtab, 0, 4);
+               ret = fread(stringtab + 4, 1, i - 4, f);
+               my_assert(ret, i - 4);
+
+               ret = fseek(f, hdr.f_symptr, SEEK_SET);
+               my_assert(ret, 0);
+       }
+
+       for (i = s = 0; i < hdr.f_nsyms; i++) {
+               long pos = ftell(f);
+
+               ret = fread(&syment, 1, sizeof(syment), f);
+               my_assert(ret, sizeof(syment));
+
+               strncpy(symname, syment.e.e_name, 8);
+               //printf("%3d %2d %08x '%s'\n", syment.e_sclass,
+               //      syment.e_scnum, syment.e_value, symname);
+
+               if (syment.e_scnum != text_scnum || syment.e_sclass != C_EXT)
+                       continue;
+
+               symt_o[s].addr = syment.e_value;
+               symt_o[s].fpos = pos;
+               if (syment.e.e.e_zeroes == 0)
+                       symt_o[s].name = stringtab + syment.e.e.e_offset;
+               else
+                       symt_o[s].name = strdup(symname);
+               s++;
+
+               if (syment.e_numaux) {
+                       ret = fseek(f, syment.e_numaux * sizeof(syment),
+                                   SEEK_CUR);
+                       my_assert(ret, 0);
+                       i += syment.e_numaux;
+               }
+       }
+
+       if (symt_o != NULL)
+               qsort(symt_o, s, sizeof(symt_o[0]), symt_cmp);
+
+       *sym_cnt = s;
+       *symtab_out = symt_o;
+
+       if (base != 0 && base_out != NULL)
                *base_out = base + scnhdr.s_vaddr;
 }
 
@@ -352,16 +460,18 @@ int main(int argc, char *argv[])
        long text_ofs_obj, text_ofs_exe;
        long sztext_obj, sztext_exe, sztext_cmn;
        RELOC *relocs_obj, *relocs_exe;
-       long reloc_cnt_obj, reloc_cnt_exe, reloc_cnt_cmn;
-       unsigned int base = 0;
+       long reloc_cnt_obj, reloc_cnt_exe;
+       struct my_symtab *syms_obj, *syms_exe;
+       long sym_cnt_obj, sym_cnt_exe;
        uint8_t *d_obj, *d_exe;
+       unsigned int base = 0;
        int retval = 1;
        int left;
        int ret;
        int i;
 
        if (argc != 3) {
-               printf("usage:\n%s <obj> <exe>\n", argv[0]);
+               printf("usage:\n%s <a_obj> <exe>\n", argv[0]);
                return 1;
        }
 
@@ -374,22 +484,19 @@ int main(int argc, char *argv[])
 
        f_exe = fopen(argv[2], "r");
        if (f_exe == NULL) {
-               fprintf(stderr, "%s", argv[1]);
+               fprintf(stderr, "%s", argv[2]);
                perror("");
                return 1;
        }
 
-       parse_headers(f_obj, &base, &text_ofs_obj, &d_obj, &sztext_obj,
-               &relocs_obj, &reloc_cnt_obj);
+       parse_headers(f_obj, NULL, &text_ofs_obj, &d_obj, &sztext_obj,
+               &relocs_obj, &reloc_cnt_obj, &syms_obj, &sym_cnt_obj);
        parse_headers(f_exe, &base, &text_ofs_exe, &d_exe, &sztext_exe,
-               &relocs_exe, &reloc_cnt_exe);
+               &relocs_exe, &reloc_cnt_exe, &syms_exe, &sym_cnt_exe);
 
        sztext_cmn = sztext_obj;
        if (sztext_cmn > sztext_exe)
                sztext_cmn = sztext_exe;
-       reloc_cnt_cmn = reloc_cnt_obj;
-       if (reloc_cnt_cmn > reloc_cnt_exe)
-               reloc_cnt_cmn = reloc_cnt_exe;
 
        if (sztext_cmn == 0) {
                printf("bad .text size(s): %ld, %ld\n",
@@ -397,7 +504,7 @@ int main(int argc, char *argv[])
                return 1;
        }
 
-       for (i = 0; i < reloc_cnt_obj; i++) // reloc_cnt_cmn
+       for (i = 0; i < reloc_cnt_obj; i++)
        {
                unsigned int a = relocs_obj[i].r_vaddr;
                //printf("%04x %08x\n", relocs_obj[i].r_type, a);