Initial revision

CVS patchset: 5498
CVS date: 2002/06/17 16:38:22

1 files changed, 170 insertions, 0 deletions

diff --git a/libelf/nlist.c b/libelf/nlist.c
new file mode 100755
index 000000000..f94432fb4
--- /dev/null
+++ b/libelf/nlist.c
@@ -0,0 +1,170 @@
+/*
+nlist.c - implementation of the nlist(3) function.
+Copyright (C) 1995 Michael Riepe <riepe@ifwsn4.ifw.uni-hannover.de>
+
+This library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public
+License as published by the Free Software Foundation; either
+version 2 of the License, or (at your option) any later version.
+
+This library 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
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with this library; if not, write to the Free Software
+Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+*/
+
+#include <private.h>
+#include <nlist.h>
+#include <fcntl.h>
+
+struct hash {
+    const char* name;
+    unsigned long   hash;
+    Elf32_Sym*	sym;
+};
+
+static int
+_elf_nlist(Elf *elf, struct nlist *nl) {
+    Elf_Scn *symtab = NULL;
+    Elf_Scn *strtab = NULL;
+    Elf_Data *symdata;
+    Elf_Data *strdata;
+    Elf32_Ehdr *ehdr;
+    Elf32_Shdr *shdr;
+    Elf_Scn *scn;
+    Elf32_Sym *symbols;
+    const char *strings;
+    unsigned nsymbols;
+    unsigned nstrings;
+    unsigned i;
+    const char *name;
+    struct hash *table;
+    unsigned nhash;
+    unsigned long hash;
+    unsigned long j;
+
+    if (!(ehdr = elf32_getehdr(elf))) {
+	return -1;
+    }
+    scn = NULL;
+    while ((scn = elf_nextscn(elf, scn))) {
+	if (!(shdr = elf32_getshdr(scn))) {
+	    return -1;
+	}
+	if (shdr->sh_type == SHT_SYMTAB) {
+	    strtab = elf_getscn(elf, shdr->sh_link);
+	    symtab = scn;
+	    break;
+	}
+	if (shdr->sh_type == SHT_DYNSYM) {
+	    strtab = elf_getscn(elf, shdr->sh_link);
+	    symtab = scn;
+	}
+    }
+    if (elf_errno()) {
+	return -1;
+    }
+    symdata = elf_getdata(symtab, NULL);
+    strdata = elf_getdata(strtab, NULL);
+    if (!symdata || !strdata) {
+	return -1;
+    }
+    symbols = (Elf32_Sym*)symdata->d_buf;
+    strings = (const char*)strdata->d_buf;
+    nsymbols = symdata->d_size / sizeof(Elf32_Sym);
+    nstrings = strdata->d_size;
+    if (!symbols || !strings || !nsymbols || !nstrings) {
+	return -1;
+    }
+
+    /*
+     * build a simple hash table
+     */
+    nhash = 3 * nsymbols - 4;
+    if (!(table = (struct hash*)malloc(nhash * sizeof(*table)))) {
+	return -1;
+    }
+    for (i = 0; i < nhash; i++) {
+	table[i].name = NULL;
+    }
+    for (i = 1; i < nsymbols; i++) {
+	if (symbols[i].st_name < 0 && symbols[i].st_name >= nstrings) {
+	    free(table);
+	    return -1;
+	}
+	if (symbols[i].st_name == 0) {
+	    continue;
+	}
+	name = strings + symbols[i].st_name;
+	hash = elf_hash(name);
+	for (j = hash; table[j %= nhash].name; j += 3) {
+	    if (table[j].hash != hash) {
+		continue;
+	    }
+	    if (table[j].name == name || !strcmp(table[j].name, name)) {
+		break;
+	    }
+	}
+	table[j].hash = hash;
+	table[j].name = name;
+	table[j].sym = &symbols[i];
+    }
+
+    /*
+     * symbol lookup
+     */
+    for (i = 0; (name = nl[i].n_name) && *name; i++) {
+	hash = elf_hash(name);
+	for (j = hash; table[j %= nhash].name; j += 3) {
+	    if (table[j].hash == hash && !strcmp(table[j].name, name)) {
+		break;
+	    }
+	}
+	if (table[j].name) {
+	    nl[i].n_value = table[j].sym->st_value;
+	    nl[i].n_scnum = table[j].sym->st_shndx;
+	}
+	else {
+	    nl[i].n_value = 0;
+	    nl[i].n_scnum = 0;
+	}
+	/*
+	 * this needs more work
+	 */
+	nl[i].n_type = 0;
+	nl[i].n_sclass = 0;
+	nl[i].n_numaux = 0;
+    }
+    free(table);
+    return 0;
+}
+
+int
+nlist(const char *filename, struct nlist *nl) {
+    int result = -1;
+    unsigned oldver;
+    Elf *elf;
+    int fd;
+
+    if ((oldver = elf_version(EV_CURRENT)) != EV_NONE) {
+	if ((fd = open(filename, O_RDONLY)) != -1) {
+	    if ((elf = elf_begin(fd, ELF_C_READ, NULL))) {
+		result = _elf_nlist(elf, nl);
+		elf_end(elf);
+	    }
+	    close(fd);
+	}
+	elf_version(oldver);
+    }
+    if (result) {
+	while (nl->n_name && *nl->n_name) {
+	    nl->n_value = 0;
+	    nl++;
+	}
+    }
+    return result;
+}