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(_dl_map_object_from_fd): Get file header with read instead of mmap.

This commit is contained in:
Ulrich Drepper 1998-05-21 15:30:48 +00:00
parent c9a6737636
commit 32c85e43ed
1 changed files with 24 additions and 30 deletions
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54
elf/dl-load.c
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@ -107,6 +107,10 @@ static size_t ncapstr;
static size_t max_capstrlen;
/* This function has no public prototype. */
extern ssize_t __libc_read (int, void *, size_t);
/* Local version of `strdup' function. */
static inline char *
local_strdup (const char *s)
@ -497,15 +501,11 @@ _dl_map_object_from_fd (char *name, int fd, char *realname,
struct link_map *loader, int l_type)
{
struct link_map *l = NULL;
void *file_mapping = NULL;
size_t mapping_size = 0;
#define LOSE(s) lose (0, (s))
void lose (int code, const char *msg)
{
(void) __close (fd);
if (file_mapping)
__munmap (file_mapping, mapping_size);
if (l)
{
/* Remove the stillborn object from the list and free it. */
@ -532,30 +532,13 @@ _dl_map_object_from_fd (char *name, int fd, char *realname,
return mapat;
}
/* Make sure LOCATION is mapped in. */
void *map (off_t location, size_t size)
{
if ((off_t) mapping_size <= location + (off_t) size)
{
void *result;
if (file_mapping)
__munmap (file_mapping, mapping_size);
mapping_size = (location + size + 1 + _dl_pagesize - 1);
mapping_size &= ~(_dl_pagesize - 1);
result = __mmap (file_mapping, mapping_size, PROT_READ,
MAP_COPY|MAP_FILE, fd, 0);
if (result == MAP_FAILED)
lose (errno, "cannot map file data");
file_mapping = result;
}
return file_mapping + location;
}
const ElfW(Ehdr) *header;
const ElfW(Phdr) *phdr;
const ElfW(Phdr) *ph;
size_t maplength;
int type;
char *readbuf;
ssize_t readlength;
/* Look again to see if the real name matched another already loaded. */
for (l = _dl_loaded; l; l = l->l_next)
@ -577,8 +560,12 @@ _dl_map_object_from_fd (char *name, int fd, char *realname,
if (_dl_debug_files)
_dl_debug_message (1, "file=", name, "; generating link map\n", NULL);
/* Map in the first page to read the header. */
header = map (0, sizeof *header);
/* Read the header directly. */
readbuf = alloca (_dl_pagesize);
readlength = __libc_read (fd, readbuf, _dl_pagesize);
if (readlength < sizeof(*header))
lose (errno, "cannot read file data");
header = (void *) readbuf;
/* Check the header for basic validity. */
if (*(Elf32_Word *) &header->e_ident !=
@ -631,11 +618,21 @@ _dl_map_object_from_fd (char *name, int fd, char *realname,
l->l_loader = loader;
/* Extract the remaining details we need from the ELF header
and then map in the program header table. */
and then read in the program header table. */
l->l_entry = header->e_entry;
type = header->e_type;
l->l_phnum = header->e_phnum;
phdr = map (header->e_phoff, l->l_phnum * sizeof (ElfW(Phdr)));
maplength = header->e_phnum * sizeof (ElfW(Phdr));
if (header->e_phoff + maplength <= readlength)
phdr = (void *) (readbuf + header->e_phoff);
else
{
phdr = alloca (maplength);
__lseek (fd, SEEK_SET, header->e_phoff);
if (__libc_read (fd, (void *) phdr, maplength) != maplength)
lose (errno, "cannot read file data");
}
{
/* Scan the program header table, collecting its load commands. */
@ -689,9 +686,6 @@ _dl_map_object_from_fd (char *name, int fd, char *realname,
}
}
/* We are done reading the file's headers now. Unmap them. */
__munmap (file_mapping, mapping_size);
/* Now process the load commands and map segments into memory. */
c = loadcmds;