Merge "Use mmap to read an initial ELF header of library"
diff --git a/linker/linker.c b/linker/linker.c
index eb9cc3e..739d3e4 100644
--- a/linker/linker.c
+++ b/linker/linker.c
@@ -640,10 +640,6 @@
return -1;
}
-/* temporary space for holding the first page of the shared lib
- * which contains the elf header (with the pht). */
-static unsigned char __header[PAGE_SIZE];
-
typedef struct {
long mmap_addr;
char tag[4]; /* 'P', 'R', 'E', ' ' */
@@ -1086,29 +1082,34 @@
unsigned ext_sz;
unsigned req_base;
const char *bname;
+ struct stat sb;
soinfo *si = NULL;
- Elf32_Ehdr *hdr;
+ Elf32_Ehdr *hdr = MAP_FAILED;
- if(fd == -1) {
+ if (fd == -1) {
DL_ERR("Library '%s' not found", name);
return NULL;
}
- /* We have to read the ELF header to figure out what to do with this image
+ /* We have to read the ELF header to figure out what to do with this image.
+ * Map entire file for this. There won't be much difference in physical
+ * memory usage or performance.
*/
- if (lseek(fd, 0, SEEK_SET) < 0) {
- DL_ERR("lseek() failed!");
+ if (fstat(fd, &sb) < 0) {
+ DL_ERR("%5d fstat() failed! (%s)", pid, strerror(errno));
goto fail;
}
- if ((cnt = read(fd, &__header[0], PAGE_SIZE)) < 0) {
- DL_ERR("read() failed!");
+ hdr = mmap(NULL, sb.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
+ if (hdr == MAP_FAILED) {
+ DL_ERR("%5d failed to mmap() header of '%s' (%s)",
+ pid, name, strerror(errno));
goto fail;
}
/* Parse the ELF header and get the size of the memory footprint for
* the library */
- req_base = get_lib_extents(fd, name, &__header[0], &ext_sz);
+ req_base = get_lib_extents(fd, name, hdr, &ext_sz);
if (req_base == (unsigned)-1)
goto fail;
TRACE("[ %5d - '%s' (%s) wants base=0x%08x sz=0x%08x ]\n", pid, name,
@@ -1138,22 +1139,20 @@
pid, name, (void *)si->base, (unsigned) ext_sz);
/* Now actually load the library's segments into right places in memory */
- if (load_segments(fd, &__header[0], si) < 0) {
+ if (load_segments(fd, hdr, si) < 0) {
goto fail;
}
- /* this might not be right. Technically, we don't even need this info
- * once we go through 'load_segments'. */
- hdr = (Elf32_Ehdr *)si->base;
si->phdr = (Elf32_Phdr *)((unsigned char *)si->base + hdr->e_phoff);
si->phnum = hdr->e_phnum;
- /**/
+ munmap(hdr, sb.st_size);
close(fd);
return si;
fail:
if (si) free_info(si);
+ if (hdr != MAP_FAILED) munmap(hdr, sb.st_size);
close(fd);
return NULL;
}
@@ -1678,7 +1677,7 @@
if (si->flags & (FLAG_EXE | FLAG_LINKER)) {
/* Locate the needed program segments (DYNAMIC/ARM_EXIDX) for
- * linkage info if this is the executable or the linker itself.
+ * linkage info if this is the executable or the linker itself.
* If this was a dynamic lib, that would have been done at load time.
*
* TODO: It's unfortunate that small pieces of this are