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libctf: give up "for now" on using libelf to add a section to an existing file 

And use what worked so far, that is: if the section is already there,
replacing its contents works, because probably all the relocation was
done... If not, be a chicken and call system("objcopy..."), but...
I'llll be bahck!

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Arnaldo Carvalho de Melo 2009-03-19 19:41:14 -03:00
parent f2495cd1a6
commit dcef613288
1 changed files with 145 additions and 8 deletions
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153
libctf.c
View File

@ -1,8 +1,10 @@
#include <fcntl.h>
#include <gelf.h>
#include <limits.h>
#include <malloc.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <zlib.h>
@ -398,8 +400,8 @@ int ctf__encode(struct ctf *self, uint8_t flags)
{
struct ctf_header *hdr;
unsigned int size;
const void *bf;
int fd;
void *bf;
int err = -1;
size = gobuffer__size(&self->types) + gobuffer__size(self->strings);
self->size = sizeof(*hdr) + size;
@ -428,11 +430,19 @@ int ctf__encode(struct ctf *self, uint8_t flags)
*(char *)(self->buf + sizeof(*hdr) + hdr->ctf_str_off) = '\0';
if (flags & CTF_FLAGS_COMPR) {
bf = ctf__compress(self->buf + sizeof(*hdr), &size);
bf = (void *)ctf__compress(self->buf + sizeof(*hdr), &size);
if (bf == NULL) {
fprintf(stderr, "%s: ctf__compress failed!\n", __func__);
printf("%s: ctf__compress failed!\n", __func__);
return -ENOMEM;
}
void *new_bf = malloc(sizeof(*hdr) + size);
if (new_bf == NULL)
return -ENOMEM;
memcpy(new_bf, hdr, sizeof(*hdr));
memcpy(new_bf + sizeof(*hdr), bf, size);
free(bf);
bf = new_bf;
size += sizeof(*hdr);
} else {
bf = self->buf;
size = self->size;
@ -445,15 +455,142 @@ int ctf__encode(struct ctf *self, uint8_t flags)
gobuffer__nr_entries(self->strings),
gobuffer__size(self->strings), size);
#endif
int fd = open(self->filename, O_RDWR);
if (fd < 0) {
fprintf(stderr, "Cannot open %s\n", self->filename);
return -1;
}
if (elf_version(EV_CURRENT) == EV_NONE) {
fprintf(stderr, "Cannot set libelf version.\n");
goto out_close;
}
Elf *elf = elf_begin(fd, ELF_C_RDWR, NULL);
if (elf == NULL) {
fprintf(stderr, "Cannot update ELF file.\n");
goto out_close;
}
elf_flagelf(elf, ELF_C_SET, ELF_F_DIRTY);
GElf_Ehdr ehdr_mem;
GElf_Ehdr *ehdr = gelf_getehdr(elf, &ehdr_mem);
if (ehdr == NULL) {
fprintf(stderr, "%s: elf_getehdr failed.\n", __func__);
goto out_close;
}
/*
* First we look if there was already a .SUNW_ctf section to overwrite.
*/
Elf_Data *data = NULL;
size_t strndx;
GElf_Shdr shdr_mem;
GElf_Shdr *shdr;
Elf_Scn *scn = NULL;
elf_getshstrndx(elf, &strndx);
while ((scn = elf_nextscn(elf, scn)) != NULL) {
shdr = gelf_getshdr(scn, &shdr_mem);
if (shdr == NULL)
continue;
char *secname = elf_strptr(elf, strndx, shdr->sh_name);
if (strcmp(secname, ".SUNW_ctf") == 0) {
data = elf_getdata(scn, data);
goto out_update;
}
}
/* FIXME
* OK, if we have the section, that is ok, we can just replace the
* data, if not, I made a mistake on the small amount of boilerplate
* below, probably .relA.ted to relocations...
*/
#if 0
/* Now we look if the ".SUNW_ctf" string is in the strings table */
scn = elf_getscn(elf, strndx);
shdr = gelf_getshdr(scn, &shdr_mem);
data = elf_getdata(scn, data);
fprintf(stderr, "Looking for the string\n");
size_t ctf_name_offset = 1; /* First byte is '\0' */
while (ctf_name_offset < data->d_size) {
const char *cur_str = data->d_buf + ctf_name_offset;
fprintf(stderr, "*-> %s\n", cur_str);
if (strcmp(cur_str, ".SUNW_ctf") == 0)
goto found_SUNW_ctf_str;
ctf_name_offset += strlen(cur_str) + 1;
}
/* Add the section name */
const size_t ctf_name_len = strlen(".SUNW_ctf") + 1;
char *new_strings_table = malloc(data->d_size + ctf_name_len);
if (new_strings_table == NULL)
goto out_close;
memcpy(new_strings_table, data->d_buf, data->d_size);
strcpy(new_strings_table + data->d_size, ".SUNW_ctf");
ctf_name_offset = data->d_size;
data->d_size += ctf_name_len;
data->d_buf = new_strings_table;
elf_flagdata(data, ELF_C_SET, ELF_F_DIRTY);
elf_flagshdr(scn, ELF_C_SET, ELF_F_DIRTY);
Elf_Scn *newscn;
found_SUNW_ctf_str:
newscn = elf_newscn(elf);
if (newscn == NULL)
goto out_close;
data = elf_newdata(newscn);
if (data == NULL)
goto out_close;
shdr = gelf_getshdr(newscn, &shdr_mem);
shdr->sh_name = ctf_name_offset;
shdr->sh_type = SHT_PROGBITS;
gelf_update_shdr(newscn, &shdr_mem);
elf_flagshdr(newscn, ELF_C_SET, ELF_F_DIRTY);
#else
char pathname[PATH_MAX];
snprintf(pathname, sizeof(pathname), "%s.SUNW_ctf", self->filename);
fd = creat(pathname, S_IRUSR | S_IWUSR);
if (fd == -1) {
fprintf(stderr, "%s: open(%s) failed!\n", __func__, pathname);
return -1;
goto out_close;
}
write(fd, hdr, sizeof(*hdr));
write(fd, bf, size);
if (write(fd, bf, size) != size)
goto out_close;
if (close(fd) < 0)
goto out_unlink;
char cmd[PATH_MAX];
snprintf(cmd, sizeof(cmd), "objcopy --add-section .SUNW_ctf=%s %s",
pathname, self->filename);
if (system(cmd) == 0)
err = 0;
out_unlink:
unlink(pathname);
return err;
#endif
out_update:
data->d_buf = bf;
data->d_size = size;
elf_flagdata(data, ELF_C_SET, ELF_F_DIRTY);
if (elf_update(elf, ELF_C_NULL) < 0)
goto out_close;
if (elf_update(elf, ELF_C_WRITE) < 0)
goto out_close;
elf_end(elf);
err = 0;
out_close:
close(fd);
return 0;
return err;
}