+#define HEADER_FUNCTIONS(CLASS) \
+ \
+/* readelfheader() reads the ELF header into our global variable, and \
+ * checks to make sure that this is in fact a file that we should be \
+ * munging. \
+ */ \
+static int readelfheader ## CLASS (int fd, Elf ## CLASS ## _Ehdr *ehdr) \
+{ \
+ if (read(fd, ((char *)ehdr)+EI_NIDENT, sizeof(*ehdr) - EI_NIDENT) \
+ != sizeof(*ehdr) - EI_NIDENT) \
+ return ferr("missing or incomplete ELF header."); \
+ \
+ /* Verify the sizes of the ELF header and the program segment \
+ * header table entries. \
+ */ \
+ if (EGET(ehdr->e_ehsize) != sizeof(Elf ## CLASS ## _Ehdr)) \
+ return err("unrecognized ELF header size."); \
+ if (EGET(ehdr->e_phentsize) != sizeof(Elf ## CLASS ## _Phdr)) \
+ return err("unrecognized program segment header size."); \
+ \
+ /* Finally, check the file type. \
+ */ \
+ if (EGET(ehdr->e_type) != ET_EXEC && EGET(ehdr->e_type) != ET_DYN) \
+ return err("not an executable or shared-object library."); \
+ \
+ return TRUE; \
+} \
+ \
+/* readphdrtable() loads the program segment header table into memory. \
+ */ \
+static int readphdrtable ## CLASS (int fd, Elf ## CLASS ## _Ehdr const *ehdr, \
+ Elf ## CLASS ## _Phdr **phdrs) \
+{ \
+ size_t size; \
+ \
+ if (!EGET(ehdr->e_phoff) || !EGET(ehdr->e_phnum) \
+) return err("ELF file has no program header table."); \
+ \
+ size = EGET(ehdr->e_phnum) * sizeof **phdrs; \
+ if (!(*phdrs = malloc(size))) \
+ return err("Out of memory!"); \
+ \
+ errno = 0; \
+ if (read(fd, *phdrs, size) != (ssize_t)size) \
+ return ferr("missing or incomplete program segment header table."); \
+ \
+ return TRUE; \
+} \
+ \
+/* getmemorysize() determines the offset of the last byte of the file \
+ * that is referenced by an entry in the program segment header table. \
+ * (Anything in the file after that point is not used when the program \
+ * is executing, and thus can be safely discarded.) \
+ */ \
+static int getmemorysize ## CLASS (Elf ## CLASS ## _Ehdr const *ehdr, \
+ Elf ## CLASS ## _Phdr const *phdrs, \
+ unsigned long *newsize) \
+{ \
+ Elf ## CLASS ## _Phdr const *phdr; \
+ unsigned long size, n; \
+ int i; \
+ \
+ /* Start by setting the size to include the ELF header and the \
+ * complete program segment header table. \
+ */ \
+ size = EGET(ehdr->e_phoff) + EGET(ehdr->e_phnum) * sizeof *phdrs; \
+ if (size < sizeof *ehdr) \
+ size = sizeof *ehdr; \
+ \
+ /* Then keep extending the size to include whatever data the \
+ * program segment header table references. \
+ */ \
+ for (i = 0, phdr = phdrs ; i < EGET(ehdr->e_phnum) ; ++i, ++phdr) { \
+ if (EGET(phdr->p_type) != PT_NULL) { \
+ n = EGET(phdr->p_offset) + EGET(phdr->p_filesz); \
+ if (n > size) \
+ size = n; \
+ } \
+ } \
+ \
+ *newsize = size; \
+ return TRUE; \
+} \
+ \
+/* modifyheaders() removes references to the section header table if \
+ * it was stripped, and reduces program header table entries that \
+ * included truncated bytes at the end of the file. \
+ */ \
+static int modifyheaders ## CLASS (Elf ## CLASS ## _Ehdr *ehdr, \
+ Elf ## CLASS ## _Phdr *phdrs, \
+ unsigned long newsize) \
+{ \
+ Elf ## CLASS ## _Phdr *phdr; \
+ int i; \
+ \
+ /* If the section header table is gone, then remove all references \
+ * to it in the ELF header. \
+ */ \
+ if (EGET(ehdr->e_shoff) >= newsize) { \
+ ESET(ehdr->e_shoff,0); \
+ ESET(ehdr->e_shnum,0); \
+ ESET(ehdr->e_shentsize,0); \
+ ESET(ehdr->e_shstrndx,0); \
+ } \
+ \
+ /* The program adjusts the file size of any segment that was \
+ * truncated. The case of a segment being completely stripped out \
+ * is handled separately. \
+ */ \
+ for (i = 0, phdr = phdrs ; i < EGET(ehdr->e_phnum) ; ++i, ++phdr) { \
+ if (EGET(phdr->p_offset) >= newsize) { \
+ ESET(phdr->p_offset,newsize); \
+ ESET(phdr->p_filesz,0); \
+ } else if (EGET(phdr->p_offset) + EGET(phdr->p_filesz) > newsize) { \
+ newsize -= EGET(phdr->p_offset); \
+ ESET(phdr->p_filesz, newsize); \
+ } \
+ } \
+ \
+ return TRUE; \
+} \
+ \
+/* commitchanges() writes the new headers back to the original file \
+ * and sets the file to its new size. \
+ */ \
+static int commitchanges ## CLASS (int fd, Elf ## CLASS ## _Ehdr const *ehdr, \
+ Elf ## CLASS ## _Phdr *phdrs, \
+ unsigned long newsize) \
+{ \
+ size_t n; \
+ \
+ /* Save the changes to the ELF header, if any. \
+ */ \
+ if (lseek(fd, 0, SEEK_SET)) \
+ return ferr("could not rewind file"); \
+ errno = 0; \
+ if (write(fd, ehdr, sizeof *ehdr) != sizeof *ehdr) \
+ return err("could not modify file"); \
+ \
+ /* Save the changes to the program segment header table, if any. \
+ */ \
+ if (lseek(fd, EGET(ehdr->e_phoff), SEEK_SET) == (off_t)-1) { \
+ err("could not seek in file."); \
+ goto warning; \
+ } \
+ n = EGET(ehdr->e_phnum) * sizeof *phdrs; \
+ if (write(fd, phdrs, n) != (ssize_t)n) { \
+ err("could not write to file"); \
+ goto warning; \
+ } \
+ \
+ /* Eleventh-hour sanity check: don't truncate before the end of \
+ * the program segment header table. \
+ */ \
+ if (newsize < EGET(ehdr->e_phoff) + n) \
+ newsize = EGET(ehdr->e_phoff) + n; \
+ \
+ /* Chop off the end of the file. \
+ */ \
+ if (ftruncate(fd, newsize)) { \
+ err("could not resize file"); \
+ goto warning; \
+ } \
+ \
+ return TRUE; \
+ \
+ warning: \
+ return err("ELF file may have been corrupted!"); \
projects / openwrt.git / blobdiff