Hello list,
On behalf of Pete Chou, I would like to ask for review, testing and hopefully
commit help of this revised patch for crunchgen and crunchide which allows
mclinker (http://code.google.com/p/mclinker/) to link the base system. In
short, this patch is needed because crunchide is being overly strict about the
section layout of an object file.
Thanks,
Erik
Index: exec_elf32.c
===================================================================
--- exec_elf32.c (revision 244199)
+++ exec_elf32.c (working copy)
@@ -45,6 +45,7 @@
#include <sys/stat.h>
#include <errno.h>
+#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
@@ -82,11 +83,9 @@
#define xe32toh(x) ((data == ELFDATA2MSB) ? be32toh(x) :
le32toh(x))
#define htoxe32(x) ((data == ELFDATA2MSB) ? htobe32(x) :
htole32(x))
-struct listelem {
- struct listelem *next;
- void *mem;
- off_t file;
- size_t size;
+struct shlayout {
+ Elf_Shdr *shdr;
+ void *bufp;
};
static ssize_t
@@ -235,17 +234,20 @@
ELFNAMEEND(hide)(int fd, const char *fn)
{
Elf_Ehdr ehdr;
- Elf_Shdr *shdrp = NULL, *symtabshdr, *strtabshdr;
+ struct shlayout *layoutp = NULL;
+ Elf_Shdr *shdrp = NULL, *symtabshdr, *strtabshdr, *shstrtabshdr;
+ Elf_Shdr shdrshdr;
Elf_Sym *symtabp = NULL;
- char *strtabp = NULL;
- Elf_Size nsyms, ewi;
+ char *shstrtabp = NULL, *strtabp = NULL;
+ Elf_Size nsyms, ewi;
+ Elf_Off off;
ssize_t shdrsize;
- int rv, i, weird;
- size_t nstrtab_size, nstrtab_nextoff, fn_size;
+ int rv, i, weird, l, m, r, strtabidx;
+ size_t nstrtab_size, nstrtab_nextoff, fn_size, size;
char *nstrtabp = NULL;
unsigned char data;
- Elf_Off maxoff, stroff;
const char *weirdreason = NULL;
+ void *buf;
rv = 0;
if (xreadatoff(fd, &ehdr, 0, sizeof ehdr, fn) != sizeof ehdr)
@@ -260,63 +262,124 @@
shdrsize)
goto bad;
- symtabshdr = strtabshdr = NULL;
+ symtabshdr = strtabshdr = shstrtabshdr = NULL;
weird = 0;
- maxoff = stroff = 0;
for (i = 0; i < xe16toh(ehdr.e_shnum); i++) {
- if (xewtoh(shdrp[i].sh_offset) > maxoff)
- maxoff = xewtoh(shdrp[i].sh_offset);
switch (xe32toh(shdrp[i].sh_type)) {
case SHT_SYMTAB:
- if (symtabshdr != NULL)
+ if (symtabshdr != NULL) {
weird = 1;
+ weirdreason = "multiple symbol tables";
+ }
symtabshdr = &shdrp[i];
strtabshdr = &shdrp[xe32toh(shdrp[i].sh_link)];
-
- /* Check whether the string table is the last section */
- stroff =
xewtoh(shdrp[xe32toh(shdrp[i].sh_link)].sh_offset);
- if (!weird && xe32toh(shdrp[i].sh_link) !=
(xe16toh(ehdr.e_shnum) - 1)) {
- weird = 1;
- weirdreason = "string table not last section";
- }
break;
+ case SHT_STRTAB:
+ if (i == xe16toh(ehdr.e_shstrndx))
+ shstrtabshdr = &shdrp[i];
+ break;
}
}
- if (! weirdreason)
- weirdreason = "unsupported";
if (symtabshdr == NULL)
goto out;
- if (strtabshdr == NULL)
+ if (strtabshdr == NULL) {
weird = 1;
- if (!weird && stroff != maxoff) {
+ weirdreason = "string table does not exist";
+ }
+ if (shstrtabshdr == NULL) {
weird = 1;
- weirdreason = "string table section not last in file";
- }
+ weirdreason = "section header string table does not exist";
+ }
+ if (weirdreason == NULL)
+ weirdreason = "unsupported";
if (weird) {
fprintf(stderr, "%s: weird executable (%s)\n", fn, weirdreason);
goto bad;
}
/*
+ * sort section layout table by offset
+ */
+ layoutp = xmalloc(sizeof(struct shlayout) * (xe16toh(ehdr.e_shnum) + 1),
+ fn, "layout table");
+ if (layoutp == NULL)
+ goto bad;
+
+ /* add a pseudo entry to represent the section header table */
+ shdrshdr.sh_offset = ehdr.e_shoff;
+ shdrshdr.sh_size = htoxew(shdrsize);
+ shdrshdr.sh_addralign = htoxew(ELFSIZE / 8);
+ layoutp[xe16toh(ehdr.e_shnum)].shdr = &shdrshdr;
+
+ /* insert and sort normal section headers */
+ for (i = xe16toh(ehdr.e_shnum) - 1; i >= 0; i--) {
+ l = i + 1;
+ r = xe16toh(ehdr.e_shnum);
+ while (l <= r) {
+ m = ( l + r) / 2;
+ if (xewtoh(shdrp[i].sh_offset) >
+ xewtoh(layoutp[m].shdr->sh_offset))
+ l = m + 1;
+ else
+ r = m - 1;
+ }
+
+ if (r != i) {
+ memmove(&layoutp[i], &layoutp[i + 1],
+ sizeof(struct shlayout) * (r - i));
+ }
+
+ layoutp[r].shdr = &shdrp[i];
+ layoutp[r].bufp = NULL;
+ }
+
+ /*
* load up everything we need
*/
- /* symbol table */
- if ((symtabp = xmalloc(xewtoh(symtabshdr->sh_size), fn, "symbol table"))
- == NULL)
+ /* load section string table for debug use */
+ if ((shstrtabp = xmalloc(xewtoh(shstrtabshdr->sh_size), fn,
+ "section string table")) == NULL)
goto bad;
- if (xreadatoff(fd, symtabp, xewtoh(symtabshdr->sh_offset),
- xewtoh(symtabshdr->sh_size), fn) != xewtoh(symtabshdr->sh_size))
+ if (xreadatoff(fd, shstrtabp, xewtoh(shstrtabshdr->sh_offset),
+ xewtoh(shstrtabshdr->sh_size), fn) != xewtoh(shstrtabshdr->sh_size))
goto bad;
- /* string table */
- if ((strtabp = xmalloc(xewtoh(strtabshdr->sh_size), fn, "string table"))
- == NULL)
- goto bad;
- if (xreadatoff(fd, strtabp, xewtoh(strtabshdr->sh_offset),
- xewtoh(strtabshdr->sh_size), fn) != xewtoh(strtabshdr->sh_size))
- goto bad;
+ /* we need symtab, strtab, and everything behind strtab */
+ strtabidx = INT_MAX;
+ for (i = 0; i < xe16toh(ehdr.e_shnum) + 1; i++) {
+ if (layoutp[i].shdr == &shdrshdr) {
+ /* not load section header again */
+ layoutp[i].bufp = shdrp;
+ continue;
+ }
+ if (layoutp[i].shdr == shstrtabshdr) {
+ /* not load section string table again */
+ layoutp[i].bufp = shstrtabp;
+ continue;
+ }
+ if (layoutp[i].shdr == strtabshdr)
+ strtabidx = i;
+ if (layoutp[i].shdr == symtabshdr || i >= strtabidx) {
+ off = xewtoh(layoutp[i].shdr->sh_offset);
+ size = xewtoh(layoutp[i].shdr->sh_size);
+ layoutp[i].bufp = xmalloc(size, fn,
+ shstrtabp + xewtoh(layoutp[i].shdr->sh_name));
+ if (layoutp[i].bufp == NULL)
+ goto bad;
+ if (xreadatoff(fd, layoutp[i].bufp, off, size, fn) !=
+ size)
+ goto bad;
+
+ /* set symbol table and string table */
+ if (layoutp[i].shdr == symtabshdr)
+ symtabp = layoutp[i].bufp;
+ else if (layoutp[i].shdr == strtabshdr)
+ strtabp = layoutp[i].bufp;
+ }
+ }
+
nstrtab_size = 256;
nstrtabp = xmalloc(nstrtab_size, fn, "new string table");
if (nstrtabp == NULL)
@@ -365,26 +428,63 @@
strtabshdr->sh_size = htoxew(nstrtab_nextoff);
/*
- * write new tables to the file
+ * update section header table in ascending order of offset
*/
- if (xwriteatoff(fd, shdrp, xewtoh(ehdr.e_shoff), shdrsize, fn) !=
- shdrsize)
- goto bad;
- if (xwriteatoff(fd, symtabp, xewtoh(symtabshdr->sh_offset),
- xewtoh(symtabshdr->sh_size), fn) != xewtoh(symtabshdr->sh_size))
- goto bad;
- /* write new symbol table strings */
- if ((size_t)xwriteatoff(fd, nstrtabp, xewtoh(strtabshdr->sh_offset),
- xewtoh(strtabshdr->sh_size), fn) != xewtoh(strtabshdr->sh_size))
- goto bad;
+ for (i = strtabidx + 1; i < xe16toh(ehdr.e_shnum) + 1; i++) {
+ Elf_Off off, align;
+ off = xewtoh(layoutp[i - 1].shdr->sh_offset) +
+ xewtoh(layoutp[i - 1].shdr->sh_size);
+ align = xewtoh(layoutp[i].shdr->sh_addralign);
+ off = (off + (align - 1)) & ~(align - 1);
+ layoutp[i].shdr->sh_offset = htoxew(off);
+ }
+ /*
+ * write data to the file in descending order of offset
+ */
+ for (i = xe16toh(ehdr.e_shnum); i >= 0; i--) {
+ if (layoutp[i].shdr == strtabshdr) {
+ /* new string table */
+ buf = nstrtabp;
+ } else
+ buf = layoutp[i].bufp;
+
+ if (layoutp[i].shdr == &shdrshdr ||
+ layoutp[i].shdr == symtabshdr || i >= strtabidx) {
+ if (buf == NULL)
+ goto bad;
+
+ /*
+ * update the offset of section header table in elf
+ * header if needed.
+ */
+ if (layoutp[i].shdr == &shdrshdr &&
+ ehdr.e_shoff != shdrshdr.sh_offset) {
+ ehdr.e_shoff = shdrshdr.sh_offset;
+ off = (ELFSIZE == 32) ? 32 : 44;
+ size = sizeof(Elf_Off);
+ if (xwriteatoff(fd, &ehdr.e_shoff, off, size,
+ fn) != size)
+ goto bad;
+ }
+
+ off = xewtoh(layoutp[i].shdr->sh_offset);
+ size = xewtoh(layoutp[i].shdr->sh_size);
+ if (xwriteatoff(fd, buf, off, size, fn) != size)
+ goto bad;
+ }
+ }
+
out:
- if (shdrp != NULL)
- free(shdrp);
- if (symtabp != NULL)
- free(symtabp);
- if (strtabp != NULL)
- free(strtabp);
+ if (layoutp != NULL) {
+ for (i = 0; i < xe16toh(ehdr.e_shnum) + 1; i++) {
+ if (layoutp[i].bufp != NULL)
+ free(layoutp[i].bufp);
+ }
+ free(layoutp);
+ }
+ if (nstrtabp != NULL)
+ free(nstrtabp);
return (rv);
bad:
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