--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/agent/src/os/bsd/symtab.c	Sun Sep 25 16:03:29 2011 -0700
@@ -0,0 +1,239 @@
+/*
+ * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include <unistd.h>
+#include <search.h>
+#include <stdlib.h>
+#include <string.h>
+#include <db.h>
+#include <fcntl.h>
+#include "symtab.h"
+#include "salibelf.h"
+
+
+// ----------------------------------------------------
+// functions for symbol lookups
+// ----------------------------------------------------
+
+struct elf_section {
+  ELF_SHDR   *c_shdr;
+  void       *c_data;
+};
+
+struct elf_symbol {
+  char *name;
+  uintptr_t offset;
+  uintptr_t size;
+};
+
+typedef struct symtab {
+  char *strs;
+  size_t num_symbols;
+  struct elf_symbol *symbols;
+  DB* hash_table;
+} symtab_t;
+
+// read symbol table from given fd.
+struct symtab* build_symtab(int fd) {
+  ELF_EHDR ehdr;
+  struct symtab* symtab = NULL;
+
+  // Reading of elf header
+  struct elf_section *scn_cache = NULL;
+  int cnt = 0;
+  ELF_SHDR* shbuf = NULL;
+  ELF_SHDR* cursct = NULL;
+  ELF_PHDR* phbuf = NULL;
+  int symtab_found = 0;
+  int dynsym_found = 0;
+  uint32_t symsection = SHT_SYMTAB;
+
+  uintptr_t baseaddr = (uintptr_t)-1;
+
+  lseek(fd, (off_t)0L, SEEK_SET);
+  if (! read_elf_header(fd, &ehdr)) {
+    // not an elf
+    return NULL;
+  }
+
+  // read ELF header
+  if ((shbuf = read_section_header_table(fd, &ehdr)) == NULL) {
+    goto quit;
+  }
+
+  baseaddr = find_base_address(fd, &ehdr);
+
+  scn_cache = calloc(ehdr.e_shnum, sizeof(*scn_cache));
+  if (scn_cache == NULL) {
+    goto quit;
+  }
+
+  for (cursct = shbuf, cnt = 0; cnt < ehdr.e_shnum; cnt++) {
+    scn_cache[cnt].c_shdr = cursct;
+    if (cursct->sh_type == SHT_SYMTAB ||
+        cursct->sh_type == SHT_STRTAB ||
+        cursct->sh_type == SHT_DYNSYM) {
+      if ( (scn_cache[cnt].c_data = read_section_data(fd, &ehdr, cursct)) == NULL) {
+         goto quit;
+      }
+    }
+
+    if (cursct->sh_type == SHT_SYMTAB)
+       symtab_found++;
+
+    if (cursct->sh_type == SHT_DYNSYM)
+       dynsym_found++;
+
+    cursct++;
+  }
+
+  if (!symtab_found && dynsym_found)
+     symsection = SHT_DYNSYM;
+
+  for (cnt = 1; cnt < ehdr.e_shnum; cnt++) {
+    ELF_SHDR *shdr = scn_cache[cnt].c_shdr;
+
+    if (shdr->sh_type == symsection) {
+      ELF_SYM  *syms;
+      int j, n, rslt;
+      size_t size;
+
+      // FIXME: there could be multiple data buffers associated with the
+      // same ELF section. Here we can handle only one buffer. See man page
+      // for elf_getdata on Solaris.
+
+      // guarantee(symtab == NULL, "multiple symtab");
+      symtab = calloc(1, sizeof(*symtab));
+      if (symtab == NULL) {
+         goto quit;
+      }
+      // the symbol table
+      syms = (ELF_SYM *)scn_cache[cnt].c_data;
+
+      // number of symbols
+      n = shdr->sh_size / shdr->sh_entsize;
+
+      // create hash table, we use berkeley db to
+      // manipulate the hash table.
+      symtab->hash_table = dbopen(NULL, O_CREAT | O_RDWR, 0600, DB_HASH, NULL);
+      // guarantee(symtab->hash_table, "unexpected failure: dbopen");
+
+      // shdr->sh_link points to the section that contains the actual strings
+      // for symbol names. the st_name field in ELF_SYM is just the
+      // string table index. we make a copy of the string table so the
+      // strings will not be destroyed by elf_end.
+      size = scn_cache[shdr->sh_link].c_shdr->sh_size;
+      symtab->strs = malloc(size);
+      memcpy(symtab->strs, scn_cache[shdr->sh_link].c_data, size);
+
+      // allocate memory for storing symbol offset and size;
+      symtab->num_symbols = n;
+      symtab->symbols = calloc(n , sizeof(*symtab->symbols));
+
+      // copy symbols info our symtab and enter them info the hash table
+      for (j = 0; j < n; j++, syms++) {
+        DBT key, value;
+        char *sym_name = symtab->strs + syms->st_name;
+
+        // skip non-object and non-function symbols
+        int st_type = ELF_ST_TYPE(syms->st_info);
+        if ( st_type != STT_FUNC && st_type != STT_OBJECT)
+           continue;
+        // skip empty strings and undefined symbols
+        if (*sym_name == '\0' || syms->st_shndx == SHN_UNDEF) continue;
+
+        symtab->symbols[j].name   = sym_name;
+        symtab->symbols[j].offset = syms->st_value - baseaddr;
+        symtab->symbols[j].size   = syms->st_size;
+
+        key.data = sym_name;
+        key.size = strlen(sym_name) + 1;
+        value.data = &(symtab->symbols[j]);
+        value.size = sizeof(void *);
+        (*symtab->hash_table->put)(symtab->hash_table, &key, &value, 0);
+      }
+    }
+  }
+
+quit:
+  if (shbuf) free(shbuf);
+  if (phbuf) free(phbuf);
+  if (scn_cache) {
+    for (cnt = 0; cnt < ehdr.e_shnum; cnt++) {
+      if (scn_cache[cnt].c_data != NULL) {
+        free(scn_cache[cnt].c_data);
+      }
+    }
+    free(scn_cache);
+  }
+  return symtab;
+}
+
+void destroy_symtab(struct symtab* symtab) {
+  if (!symtab) return;
+  if (symtab->strs) free(symtab->strs);
+  if (symtab->symbols) free(symtab->symbols);
+  if (symtab->hash_table) {
+    symtab->hash_table->close(symtab->hash_table);
+  }
+  free(symtab);
+}
+
+uintptr_t search_symbol(struct symtab* symtab, uintptr_t base,
+                      const char *sym_name, int *sym_size) {
+  DBT key, value;
+  int ret;
+
+  // library does not have symbol table
+  if (!symtab || !symtab->hash_table)
+     return 0;
+
+  key.data = (char*)(uintptr_t)sym_name;
+  key.size = strlen(sym_name) + 1;
+  ret = (*symtab->hash_table->get)(symtab->hash_table, &key, &value, 0);
+  if (ret == 0) {
+    struct elf_symbol *sym = value.data;
+    uintptr_t rslt = (uintptr_t) ((char*)base + sym->offset);
+    if (sym_size) *sym_size = sym->size;
+    return rslt;
+  }
+
+quit:
+  return 0;
+}
+
+const char* nearest_symbol(struct symtab* symtab, uintptr_t offset,
+                           uintptr_t* poffset) {
+  int n = 0;
+  if (!symtab) return NULL;
+  for (; n < symtab->num_symbols; n++) {
+     struct elf_symbol* sym = &(symtab->symbols[n]);
+     if (sym->name != NULL &&
+         offset >= sym->offset && offset < sym->offset + sym->size) {
+        if (poffset) *poffset = (offset - sym->offset);
+        return sym->name;
+     }
+  }
+  return NULL;
+}