127 lines
4.4 KiB
C
127 lines
4.4 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <stdint.h>
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/* from elf.h */
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/* Type for a 16-bit quantity. */
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typedef uint16_t Elf32_Half;
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/* Types for signed and unsigned 32-bit quantities. */
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typedef uint32_t Elf32_Word;
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/* Type of addresses. */
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typedef uint32_t Elf32_Addr;
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/* Type of file offsets. */
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typedef uint32_t Elf32_Off;
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/* The ELF file header. This appears at the start of every ELF file. */
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#define EI_NIDENT (16)
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typedef struct
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{
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unsigned char e_ident[EI_NIDENT]; /* Magic number and other info */
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Elf32_Half e_type; /* Object file type */
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Elf32_Half e_machine; /* Architecture */
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Elf32_Word e_version; /* Object file version */
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Elf32_Addr e_entry; /* Entry point virtual address */
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Elf32_Off e_phoff; /* Program header table file offset */
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Elf32_Off e_shoff; /* Section header table file offset */
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Elf32_Word e_flags; /* Processor-specific flags */
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Elf32_Half e_ehsize; /* ELF header size in bytes */
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Elf32_Half e_phentsize; /* Program header table entry size */
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Elf32_Half e_phnum; /* Program header table entry count */
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Elf32_Half e_shentsize; /* Section header table entry size */
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Elf32_Half e_shnum; /* Section header table entry count */
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Elf32_Half e_shstrndx; /* Section header string table index */
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} Elf32_Ehdr;
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/* Conglomeration of the identification bytes, for easy testing as a word. */
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#define ELFMAG "\177ELF"
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#define SELFMAG 4
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#define EI_CLASS 4 /* File class byte index */
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#define ELFCLASS32 1 /* 32-bit objects */
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#define EI_DATA 5 /* Data encoding byte index */
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#define ELFDATA2MSB 2 /* 2's complement, big endian */
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/* end from elf.h */
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// This file will find all mips3 object files in an ar archive and set the ABI flags to O32
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// this allows gcc to link them with the mips2 object files.
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// Irix CC doesn't set the elf e_flags properly.
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// the AR file is structured as followed
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//"!<arch>" followed by 0x0A (linefeed) 8 characters
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// then a file header that follows the following structure
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// everything is represented using space padded characters
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// the last two characters are alwos 0x60 0x0A
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// then come the file contents
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// you can find the location of the next header by adding file_size_in_bytes (after parsing)
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// all file headers start at an even offset so if the file size in bytes is odd you have to add 1
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// the first two "files" are special. One is a symbol table with a pointer to the header of the file
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// contaning the symbol the other is an extended list of filenames
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struct ar_header {
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char identifier[16];
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char file_modification_timestamp[12];
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char owner_id[6];
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char group_id[6];
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char file_mode[8];
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char file_size_in_bytes[10];
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char ending[2];
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};
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//These constants found by inspecting output of objdump
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#define FLAGS_MIPS3 0x20
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#define FLAGS_O32ABI 0x100000
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int main(int argc, char **argv) {
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FILE *f = fopen(argv[1], "r+");
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if (f == NULL) {
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printf("Failed to open file! %s\n", argv[1]);
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return -1;
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}
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struct ar_header current_header;
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fseek(f, 0x8, SEEK_SET); // skip header, this is safe enough given that we check to make sure the
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// file header is valid
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while (1 == fread(¤t_header, sizeof(current_header), 1, f)) {
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if (current_header.ending[0] != 0x60 && current_header.ending[1] != 0x0A) {
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printf("Expected file header\n");
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return -1;
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}
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size_t filesize = atoi(current_header.file_size_in_bytes);
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Elf32_Ehdr hdr;
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if (filesize < sizeof(hdr) || (1 != fread(&hdr, sizeof(hdr), 1, f))) {
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printf("Failed to read ELF header\n");
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return -1;
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}
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if (strncmp((const char *) hdr.e_ident, ELFMAG, SELFMAG) == 0) {
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// found an ELF file.
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if (hdr.e_ident[EI_CLASS] != ELFCLASS32 || hdr.e_ident[EI_DATA] != ELFDATA2MSB) {
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printf("Expected 32bit big endian object files\n");
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return -1;
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}
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if ((hdr.e_flags & 0xFF) == FLAGS_MIPS3 && (hdr.e_flags & FLAGS_O32ABI) == 0) {
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hdr.e_flags |= FLAGS_O32ABI;
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fseek(f, -sizeof(hdr), SEEK_CUR);
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if (1 != fwrite(&hdr, sizeof(hdr), 1, f)) {
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printf("Failed to write back ELF header after patching.\n");
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return -1;
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}
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}
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}
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if (filesize % 2 == 1)
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filesize++;
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fseek(f, filesize - sizeof(hdr), SEEK_CUR);
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}
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fclose(f);
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return 0;
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}
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