/* Copyright (C) 1985, 1986, 1987, 1988, 1990, 1992 Free Software Foundation, Inc. This file is part of GNU Emacs. GNU Emacs is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNU Emacs is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GNU Emacs; see the file COPYING. If not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. In other words, you are welcome to use, share and improve this program. You are forbidden to forbid anyone else to use, share and improve what you give them. Help stamp out software-hoarding! */ /* * unexec.c - Convert a running program into an a.out file. * * Author: Spencer W. Thomas * Computer Science Dept. * University of Utah * Date: Tue Mar 2 1982 * Modified heavily since then. * * Synopsis: * unexec (new_name, a_name, data_start, bss_start, entry_address) * char *new_name, *a_name; * unsigned data_start, bss_start, entry_address; * * Takes a snapshot of the program and makes an a.out format file in the * file named by the string argument new_name. * If a_name is non-NULL, the symbol table will be taken from the given file. * On some machines, an existing a_name file is required. * * The boundaries within the a.out file may be adjusted with the data_start * and bss_start arguments. Either or both may be given as 0 for defaults. * * Data_start gives the boundary between the text segment and the data * segment of the program. The text segment can contain shared, read-only * program code and literal data, while the data segment is always unshared * and unprotected. Data_start gives the lowest unprotected address. * The value you specify may be rounded down to a suitable boundary * as required by the machine you are using. * * Specifying zero for data_start means the boundary between text and data * should not be the same as when the program was loaded. * If NO_REMAP is defined, the argument data_start is ignored and the * segment boundaries are never changed. * * Bss_start indicates how much of the data segment is to be saved in the * a.out file and restored when the program is executed. It gives the lowest * unsaved address, and is rounded up to a page boundary. The default when 0 * is given assumes that the entire data segment is to be stored, including * the previous data and bss as well as any additional storage allocated with * break (2). * * The new file is set up to start at entry_address. * * If you make improvements I'd like to get them too. * harpo!utah-cs!thomas, thomas@Utah-20 * */ /* Even more heavily modified by james@bigtex.cactus.org of Dell Computer Co. * ELF support added. * * Basic theory: the data space of the running process needs to be * dumped to the output file. Normally we would just enlarge the size * of .data, scooting everything down. But we can't do that in ELF, * because there is often something between the .data space and the * .bss space. * * In the temacs dump below, notice that the Global Offset Table * (.got) and the Dynamic link data (.dynamic) come between .data1 and * .bss. It does not work to overlap .data with these fields. * * The solution is to create a new .data segment. This segment is * filled with data from the current process. Since the contents of * various sections refer to sections by index, the new .data segment * is made the last in the table to avoid changing any existing index. * This is an example of how the section headers are changed. "Addr" * is a process virtual address. "Offset" is a file offset. raid:/nfs/raid/src/dist-18.56/src> dump -h temacs temacs: **** SECTION HEADER TABLE **** [No] Type Flags Addr Offset Size Name Link Info Adralgn Entsize [1] 1 2 0x80480d4 0xd4 0x13 .interp 0 0 0x1 0 [2] 5 2 0x80480e8 0xe8 0x388 .hash 3 0 0x4 0x4 [3] 11 2 0x8048470 0x470 0x7f0 .dynsym 4 1 0x4 0x10 [4] 3 2 0x8048c60 0xc60 0x3ad .dynstr 0 0 0x1 0 [5] 9 2 0x8049010 0x1010 0x338 .rel.plt 3 7 0x4 0x8 [6] 1 6 0x8049348 0x1348 0x3 .init 0 0 0x4 0 [7] 1 6 0x804934c 0x134c 0x680 .plt 0 0 0x4 0x4 [8] 1 6 0x80499cc 0x19cc 0x3c56f .text 0 0 0x4 0 [9] 1 6 0x8085f3c 0x3df3c 0x3 .fini 0 0 0x4 0 [10] 1 2 0x8085f40 0x3df40 0x69c .rodata 0 0 0x4 0 [11] 1 2 0x80865dc 0x3e5dc 0xd51 .rodata1 0 0 0x4 0 [12] 1 3 0x8088330 0x3f330 0x20afc .data 0 0 0x4 0 [13] 1 3 0x80a8e2c 0x5fe2c 0x89d .data1 0 0 0x4 0 [14] 1 3 0x80a96cc 0x606cc 0x1a8 .got 0 0 0x4 0x4 [15] 6 3 0x80a9874 0x60874 0x80 .dynamic 4 0 0x4 0x8 [16] 8 3 0x80a98f4 0x608f4 0x449c .bss 0 0 0x4 0 [17] 2 0 0 0x608f4 0x9b90 .symtab 18 371 0x4 0x10 [18] 3 0 0 0x6a484 0x8526 .strtab 0 0 0x1 0 [19] 3 0 0 0x729aa 0x93 .shstrtab 0 0 0x1 0 [20] 1 0 0 0x72a3d 0x68b7 .comment 0 0 0x1 0 raid:/nfs/raid/src/dist-18.56/src> dump -h xemacs xemacs: **** SECTION HEADER TABLE **** [No] Type Flags Addr Offset Size Name Link Info Adralgn Entsize [1] 1 2 0x80480d4 0xd4 0x13 .interp 0 0 0x1 0 [2] 5 2 0x80480e8 0xe8 0x388 .hash 3 0 0x4 0x4 [3] 11 2 0x8048470 0x470 0x7f0 .dynsym 4 1 0x4 0x10 [4] 3 2 0x8048c60 0xc60 0x3ad .dynstr 0 0 0x1 0 [5] 9 2 0x8049010 0x1010 0x338 .rel.plt 3 7 0x4 0x8 [6] 1 6 0x8049348 0x1348 0x3 .init 0 0 0x4 0 [7] 1 6 0x804934c 0x134c 0x680 .plt 0 0 0x4 0x4 [8] 1 6 0x80499cc 0x19cc 0x3c56f .text 0 0 0x4 0 [9] 1 6 0x8085f3c 0x3df3c 0x3 .fini 0 0 0x4 0 [10] 1 2 0x8085f40 0x3df40 0x69c .rodata 0 0 0x4 0 [11] 1 2 0x80865dc 0x3e5dc 0xd51 .rodata1 0 0 0x4 0 [12] 1 3 0x8088330 0x3f330 0x20afc .data 0 0 0x4 0 [13] 1 3 0x80a8e2c 0x5fe2c 0x89d .data1 0 0 0x4 0 [14] 1 3 0x80a96cc 0x606cc 0x1a8 .got 0 0 0x4 0x4 [15] 6 3 0x80a9874 0x60874 0x80 .dynamic 4 0 0x4 0x8 [16] 8 3 0x80c6800 0x7d800 0 .bss 0 0 0x4 0 [17] 2 0 0 0x7d800 0x9b90 .symtab 18 371 0x4 0x10 [18] 3 0 0 0x87390 0x8526 .strtab 0 0 0x1 0 [19] 3 0 0 0x8f8b6 0x93 .shstrtab 0 0 0x1 0 [20] 1 0 0 0x8f949 0x68b7 .comment 0 0 0x1 0 [21] 1 3 0x80a98f4 0x608f4 0x1cf0c .data 0 0 0x4 0 * This is an example of how the file header is changed. "Shoff" is * the section header offset within the file. Since that table is * after the new .data section, it is moved. "Shnum" is the number of * sections, which we increment. * * "Phoff" is the file offset to the program header. "Phentsize" and * "Shentsz" are the program and section header entries sizes respectively. * These can be larger than the apparent struct sizes. raid:/nfs/raid/src/dist-18.56/src> dump -f temacs temacs: **** ELF HEADER **** Class Data Type Machine Version Entry Phoff Shoff Flags Ehsize Phentsize Phnum Shentsz Shnum Shstrndx 1 1 2 3 1 0x80499cc 0x34 0x792f4 0 0x34 0x20 5 0x28 21 19 raid:/nfs/raid/src/dist-18.56/src> dump -f xemacs xemacs: **** ELF HEADER **** Class Data Type Machine Version Entry Phoff Shoff Flags Ehsize Phentsize Phnum Shentsz Shnum Shstrndx 1 1 2 3 1 0x80499cc 0x34 0x96200 0 0x34 0x20 5 0x28 22 19 * These are the program headers. "Offset" is the file offset to the * segment. "Vaddr" is the memory load address. "Filesz" is the * segment size as it appears in the file, and "Memsz" is the size in * memory. Below, the third segment is the code and the fourth is the * data: the difference between Filesz and Memsz is .bss raid:/nfs/raid/src/dist-18.56/src> dump -o temacs temacs: ***** PROGRAM EXECUTION HEADER ***** Type Offset Vaddr Paddr Filesz Memsz Flags Align 6 0x34 0x8048034 0 0xa0 0xa0 5 0 3 0xd4 0 0 0x13 0 4 0 1 0x34 0x8048034 0 0x3f2f9 0x3f2f9 5 0x1000 1 0x3f330 0x8088330 0 0x215c4 0x25a60 7 0x1000 2 0x60874 0x80a9874 0 0x80 0 7 0 raid:/nfs/raid/src/dist-18.56/src> dump -o xemacs xemacs: ***** PROGRAM EXECUTION HEADER ***** Type Offset Vaddr Paddr Filesz Memsz Flags Align 6 0x34 0x8048034 0 0xa0 0xa0 5 0 3 0xd4 0 0 0x13 0 4 0 1 0x34 0x8048034 0 0x3f2f9 0x3f2f9 5 0x1000 1 0x3f330 0x8088330 0 0x3e4d0 0x3e4d0 7 0x1000 2 0x60874 0x80a9874 0 0x80 0 7 0 */ /* Modified by wtien@urbana.mcd.mot.com of Motorola Inc. * * The above mechanism does not work if the unexeced ELF file is being * re-layout by other applications (such as `strip'). All the applications * that re-layout the internal of ELF will layout all sections in ascending * order of their file offsets. After the re-layout, the data2 section will * still be the LAST section in the section header vector, but its file offset * is now being pushed far away down, and causes part of it not to be mapped * in (ie. not covered by the load segment entry in PHDR vector), therefore * causes the new binary to fail. * * The solution is to modify the unexec algorithm to insert the new data2 * section header right before the new bss section header, so their file * offsets will be in the ascending order. Since some of the section's (all * sections AFTER the bss section) indexes are now changed, we also need to * modify some fields to make them point to the right sections. This is done * by macro PATCH_INDEX. All the fields that need to be patched are: * * 1. ELF header e_shstrndx field. * 2. section header sh_link and sh_info field. * 3. symbol table entry st_shndx field. * * The above example now should look like: **** SECTION HEADER TABLE **** [No] Type Flags Addr Offset Size Name Link Info Adralgn Entsize [1] 1 2 0x80480d4 0xd4 0x13 .interp 0 0 0x1 0 [2] 5 2 0x80480e8 0xe8 0x388 .hash 3 0 0x4 0x4 [3] 11 2 0x8048470 0x470 0x7f0 .dynsym 4 1 0x4 0x10 [4] 3 2 0x8048c60 0xc60 0x3ad .dynstr 0 0 0x1 0 [5] 9 2 0x8049010 0x1010 0x338 .rel.plt 3 7 0x4 0x8 [6] 1 6 0x8049348 0x1348 0x3 .init 0 0 0x4 0 [7] 1 6 0x804934c 0x134c 0x680 .plt 0 0 0x4 0x4 [8] 1 6 0x80499cc 0x19cc 0x3c56f .text 0 0 0x4 0 [9] 1 6 0x8085f3c 0x3df3c 0x3 .fini 0 0 0x4 0 [10] 1 2 0x8085f40 0x3df40 0x69c .rodata 0 0 0x4 0 [11] 1 2 0x80865dc 0x3e5dc 0xd51 .rodata1 0 0 0x4 0 [12] 1 3 0x8088330 0x3f330 0x20afc .data 0 0 0x4 0 [13] 1 3 0x80a8e2c 0x5fe2c 0x89d .data1 0 0 0x4 0 [14] 1 3 0x80a96cc 0x606cc 0x1a8 .got 0 0 0x4 0x4 [15] 6 3 0x80a9874 0x60874 0x80 .dynamic 4 0 0x4 0x8 [16] 1 3 0x80a98f4 0x608f4 0x1cf0c .data 0 0 0x4 0 [17] 8 3 0x80c6800 0x7d800 0 .bss 0 0 0x4 0 [18] 2 0 0 0x7d800 0x9b90 .symtab 19 371 0x4 0x10 [19] 3 0 0 0x87390 0x8526 .strtab 0 0 0x1 0 [20] 3 0 0 0x8f8b6 0x93 .shstrtab 0 0 0x1 0 [21] 1 0 0 0x8f949 0x68b7 .comment 0 0 0x1 0 */ #include <config.h> #include <sys/types.h> #include <stdio.h> #include <sys/stat.h> #include <memory.h> #include <string.h> #include <errno.h> #include <unistd.h> #include <fcntl.h> #include <elf.h> #include <syms.h> /* for HDRR declaration */ #include <sys/mman.h> #ifndef emacs #define fatal(a, b, c) fprintf(stderr, a, b, c), exit(1) #else extern void fatal(char *, ...); #endif /* Get the address of a particular section or program header entry, * accounting for the size of the entries. */ #define OLD_SECTION_H(n) \ (*(Elf32_Shdr *) ((byte *) old_section_h + old_file_h->e_shentsize * (n))) #define NEW_SECTION_H(n) \ (*(Elf32_Shdr *) ((byte *) new_section_h + new_file_h->e_shentsize * (n))) #define OLD_PROGRAM_H(n) \ (*(Elf32_Phdr *) ((byte *) old_program_h + old_file_h->e_phentsize * (n))) #define NEW_PROGRAM_H(n) \ (*(Elf32_Phdr *) ((byte *) new_program_h + new_file_h->e_phentsize * (n))) #define PATCH_INDEX(n) \ do { \ if ((n) >= old_bss_index) \ (n)++; } while (0) typedef unsigned char byte; /* Round X up to a multiple of Y. */ int round_up (x, y) int x, y; { int rem = x % y; if (rem == 0) return x; return x - rem + y; } /* Return the index of the section named NAME. SECTION_NAMES, FILE_NAME and FILE_H give information about the file we are looking in. If we don't find the section NAME, that is a fatal error if NOERROR is 0; we return -1 if NOERROR is nonzero. */ static int find_section (name, section_names, file_name, old_file_h, old_section_h, noerror) char *name; char *section_names; char *file_name; Elf32_Ehdr *old_file_h; Elf32_Shdr *old_section_h; int noerror; { int idx; for (idx = 1; idx < old_file_h->e_shnum; idx++) { #ifdef DEBUG fprintf (stderr, "Looking for %s - found %s\n", name, section_names + OLD_SECTION_H (idx).sh_name); #endif if (!strcmp (section_names + OLD_SECTION_H (idx).sh_name, name)) break; } if (idx == old_file_h->e_shnum) { if (noerror) return -1; else fatal ("Can't find .bss in %s.\n", file_name, 0); } return idx; } /* **************************************************************** * unexec * * driving logic. * * In ELF, this works by replacing the old .bss section with a new * .data section, and inserting an empty .bss immediately afterwards. * */ void unexec (new_name, old_name, data_start, bss_start, entry_address) char *new_name, *old_name; unsigned data_start, bss_start, entry_address; { extern unsigned int bss_end; int new_file, old_file, new_file_size; /* Pointers to the base of the image of the two files. */ caddr_t old_base, new_base; /* Pointers to the file, program and section headers for the old and new files. */ Elf32_Ehdr *old_file_h, *new_file_h; Elf32_Phdr *old_program_h, *new_program_h; Elf32_Shdr *old_section_h, *new_section_h; /* Point to the section name table in the old file. */ char *old_section_names; Elf32_Addr old_bss_addr, new_bss_addr; Elf32_Word old_bss_size, new_data2_size; Elf32_Off new_data2_offset; Elf32_Addr new_data2_addr; Elf32_Addr new_offsets_shift; int n, nn, old_bss_index, old_data_index, new_data2_index; int old_mdebug_index; struct stat stat_buf; /* Open the old file & map it into the address space. */ old_file = open (old_name, O_RDONLY); if (old_file < 0) fatal ("Can't open %s for reading: errno %d\n", old_name, errno); if (fstat (old_file, &stat_buf) == -1) fatal ("Can't fstat(%s): errno %d\n", old_name, errno); old_base = mmap (0, stat_buf.st_size, PROT_READ, MAP_SHARED, old_file, 0); if (old_base == (caddr_t) -1) fatal ("Can't mmap(%s): errno %d\n", old_name, errno); #ifdef DEBUG fprintf (stderr, "mmap(%s, %x) -> %x\n", old_name, stat_buf.st_size, old_base); #endif /* Get pointers to headers & section names. */ old_file_h = (Elf32_Ehdr *) old_base; old_program_h = (Elf32_Phdr *) ((byte *) old_base + old_file_h->e_phoff); old_section_h = (Elf32_Shdr *) ((byte *) old_base + old_file_h->e_shoff); old_section_names = (char *) old_base + OLD_SECTION_H (old_file_h->e_shstrndx).sh_offset; /* Find the mdebug section, if any. */ old_mdebug_index = find_section (".mdebug", old_section_names, old_name, old_file_h, old_section_h, 1); /* Find the old .bss section. */ old_bss_index = find_section (".bss", old_section_names, old_name, old_file_h, old_section_h, 0); /* Find the old .data section. Figure out parameters of the new data2 and bss sections. */ old_data_index = find_section (".data", old_section_names, old_name, old_file_h, old_section_h, 0); old_bss_addr = OLD_SECTION_H (old_bss_index).sh_addr; old_bss_size = OLD_SECTION_H (old_bss_index).sh_size; #if defined(emacs) || !defined(DEBUG) bss_end = (unsigned int) sbrk (0); new_bss_addr = (Elf32_Addr) bss_end; #else new_bss_addr = old_bss_addr + old_bss_size + 0x1234; #endif new_data2_addr = old_bss_addr; new_data2_size = new_bss_addr - old_bss_addr; new_data2_offset = OLD_SECTION_H (old_data_index).sh_offset + (new_data2_addr - OLD_SECTION_H (old_data_index).sh_addr); new_offsets_shift = new_bss_addr - ((old_bss_addr & ~0xfff) + ((old_bss_addr & 0xfff) ? 0x1000 : 0)); #ifdef DEBUG fprintf (stderr, "old_bss_index %d\n", old_bss_index); fprintf (stderr, "old_bss_addr %x\n", old_bss_addr); fprintf (stderr, "old_bss_size %x\n", old_bss_size); fprintf (stderr, "new_bss_addr %x\n", new_bss_addr); fprintf (stderr, "new_data2_addr %x\n", new_data2_addr); fprintf (stderr, "new_data2_size %x\n", new_data2_size); fprintf (stderr, "new_data2_offset %x\n", new_data2_offset); fprintf (stderr, "new_offsets_shift %x\n", new_offsets_shift); #endif if ((unsigned) new_bss_addr < (unsigned) old_bss_addr + old_bss_size) fatal (".bss shrank when undumping???\n", 0, 0); /* Set the output file to the right size and mmap it. Set pointers to various interesting objects. stat_buf still has old_file data. */ new_file = open (new_name, O_RDWR | O_CREAT, 0666); if (new_file < 0) fatal ("Can't creat (%s): errno %d\n", new_name, errno); new_file_size = stat_buf.st_size + old_file_h->e_shentsize + new_offsets_shift; if (ftruncate (new_file, new_file_size)) fatal ("Can't ftruncate (%s): errno %d\n", new_name, errno); new_base = mmap (0, new_file_size, PROT_READ | PROT_WRITE, MAP_SHARED, new_file, 0); if (new_base == (caddr_t) -1) fatal ("Can't mmap (%s): errno %d\n", new_name, errno); new_file_h = (Elf32_Ehdr *) new_base; new_program_h = (Elf32_Phdr *) ((byte *) new_base + old_file_h->e_phoff); new_section_h = (Elf32_Shdr *) ((byte *) new_base + old_file_h->e_shoff + new_offsets_shift); /* Make our new file, program and section headers as copies of the originals. */ memcpy (new_file_h, old_file_h, old_file_h->e_ehsize); memcpy (new_program_h, old_program_h, old_file_h->e_phnum * old_file_h->e_phentsize); /* Modify the e_shstrndx if necessary. */ PATCH_INDEX (new_file_h->e_shstrndx); /* Fix up file header. We'll add one section. Section header is further away now. */ new_file_h->e_shoff += new_offsets_shift; new_file_h->e_shnum += 1; #ifdef DEBUG fprintf (stderr, "Old section offset %x\n", old_file_h->e_shoff); fprintf (stderr, "Old section count %d\n", old_file_h->e_shnum); fprintf (stderr, "New section offset %x\n", new_file_h->e_shoff); fprintf (stderr, "New section count %d\n", new_file_h->e_shnum); #endif /* Fix up a new program header. Extend the writable data segment so that the bss area is covered too. Find that segment by looking for a segment that ends just before the .bss area. Make sure that no segments are above the new .data2. Put a loop at the end to adjust the offset and address of any segment that is above data2, just in case we decide to allow this later. */ for (n = new_file_h->e_phnum - 1; n >= 0; n--) { /* Compute maximum of all requirements for alignment of section. */ int alignment = (NEW_PROGRAM_H (n)).p_align; if ((OLD_SECTION_H (old_bss_index)).sh_addralign > alignment) alignment = OLD_SECTION_H (old_bss_index).sh_addralign; /* Supposedly this condition is okay for the SGI. */ #if 0 if (NEW_PROGRAM_H (n).p_vaddr + NEW_PROGRAM_H (n).p_filesz > old_bss_addr) fatal ("Program segment above .bss in %s\n", old_name, 0); #endif if (NEW_PROGRAM_H (n).p_type == PT_LOAD && (round_up ((NEW_PROGRAM_H (n)).p_vaddr + (NEW_PROGRAM_H (n)).p_filesz, alignment) == round_up (old_bss_addr, alignment))) break; } if (n < 0) fatal ("Couldn't find segment next to .bss in %s\n", old_name, 0); NEW_PROGRAM_H (n).p_filesz += new_offsets_shift; NEW_PROGRAM_H (n).p_memsz = NEW_PROGRAM_H (n).p_filesz; #if 1 /* Maybe allow section after data2 - does this ever happen? */ for (n = new_file_h->e_phnum - 1; n >= 0; n--) { if (NEW_PROGRAM_H (n).p_vaddr && NEW_PROGRAM_H (n).p_vaddr >= new_data2_addr) NEW_PROGRAM_H (n).p_vaddr += new_offsets_shift - old_bss_size; if (NEW_PROGRAM_H (n).p_offset >= new_data2_offset) NEW_PROGRAM_H (n).p_offset += new_offsets_shift; } #endif /* Fix up section headers based on new .data2 section. Any section whose offset or virtual address is after the new .data2 section gets its value adjusted. .bss size becomes zero and new address is set. data2 section header gets added by copying the existing .data header and modifying the offset, address and size. */ for (old_data_index = 1; old_data_index < old_file_h->e_shnum; old_data_index++) if (!strcmp (old_section_names + OLD_SECTION_H (old_data_index).sh_name, ".data")) break; if (old_data_index == old_file_h->e_shnum) fatal ("Can't find .data in %s.\n", old_name, 0); /* Walk through all section headers, insert the new data2 section right before the new bss section. */ for (n = 1, nn = 1; n < old_file_h->e_shnum; n++, nn++) { caddr_t src; /* If it is bss section, insert the new data2 section before it. */ if (n == old_bss_index) { /* Steal the data section header for this data2 section. */ memcpy (&NEW_SECTION_H (nn), &OLD_SECTION_H (old_data_index), new_file_h->e_shentsize); NEW_SECTION_H (nn).sh_addr = new_data2_addr; NEW_SECTION_H (nn).sh_offset = new_data2_offset; NEW_SECTION_H (nn).sh_size = new_data2_size; /* Use the bss section's alignment. This will assure that the new data2 section always be placed in the same spot as the old bss section by any other application. */ NEW_SECTION_H (nn).sh_addralign = OLD_SECTION_H (n).sh_addralign; /* Now copy over what we have in the memory now. */ memcpy (NEW_SECTION_H (nn).sh_offset + new_base, (caddr_t) OLD_SECTION_H (n).sh_addr, new_data2_size); nn++; memcpy (&NEW_SECTION_H (nn), &OLD_SECTION_H (n), old_file_h->e_shentsize); /* The new bss section's size is zero, and its file offset and virtual address should be off by NEW_OFFSETS_SHIFT. */ NEW_SECTION_H (nn).sh_offset += new_offsets_shift; NEW_SECTION_H (nn).sh_addr = new_bss_addr; /* Let the new bss section address alignment be the same as the section address alignment followed the old bss section, so this section will be placed in exactly the same place. */ NEW_SECTION_H (nn).sh_addralign = OLD_SECTION_H (nn).sh_addralign; NEW_SECTION_H (nn).sh_size = 0; } else { memcpy (&NEW_SECTION_H (nn), &OLD_SECTION_H (n), old_file_h->e_shentsize); /* Any section that was original placed AFTER the bss section must now be adjusted by NEW_OFFSETS_SHIFT. */ if (NEW_SECTION_H (nn).sh_offset >= new_data2_offset) NEW_SECTION_H (nn).sh_offset += new_offsets_shift; } /* If any section hdr refers to the section after the new .data section, make it refer to next one because we have inserted a new section in between. */ PATCH_INDEX (NEW_SECTION_H (nn).sh_link); /* For symbol tables, info is a symbol table index, so don't change it. */ if (NEW_SECTION_H (nn).sh_type != SHT_SYMTAB && NEW_SECTION_H (nn).sh_type != SHT_DYNSYM) PATCH_INDEX (NEW_SECTION_H (nn).sh_info); /* Now, start to copy the content of sections. */ if (NEW_SECTION_H (nn).sh_type == SHT_NULL || NEW_SECTION_H (nn).sh_type == SHT_NOBITS) continue; /* Write out the sections. .data and .data1 (and data2, called ".data" in the strings table) get copied from the current process instead of the old file. */ if (!strcmp (old_section_names + NEW_SECTION_H (nn).sh_name, ".data") || !strcmp (old_section_names + NEW_SECTION_H (nn).sh_name, ".data1") #ifdef IRIX6_5 /* Under IRIX 6.5 gcc places objects with adresses relative to shared symbols in the section .rodata, which are adjusted at startup time. Unfortunately they aren't adjusted after unexec, so with this configuration we must get .rodata also from memory. Do any other configurations need this, too? <Wolfgang.Glas@hfm.tu-graz.ac.at> 1999-06-08. */ || !strcmp (old_section_names + NEW_SECTION_H (nn).sh_name, ".rodata") #endif || !strcmp (old_section_names + NEW_SECTION_H (nn).sh_name, ".got")) src = (caddr_t) OLD_SECTION_H (n).sh_addr; else src = old_base + OLD_SECTION_H (n).sh_offset; memcpy (NEW_SECTION_H (nn).sh_offset + new_base, src, NEW_SECTION_H (nn).sh_size); /* Adjust the HDRR offsets in .mdebug and copy the line data if it's in its usual 'hole' in the object. Makes the new file debuggable with dbx. patches up two problems: the absolute file offsets in the HDRR record of .mdebug (see /usr/include/syms.h), and the ld bug that gets the line table in a hole in the elf file rather than in the .mdebug section proper. David Anderson. davea@sgi.com Jan 16,1994. */ if (n == old_mdebug_index) { #define MDEBUGADJUST(__ct,__fileaddr) \ if (n_phdrr->__ct > 0) \ { \ n_phdrr->__fileaddr += movement; \ } HDRR * o_phdrr = (HDRR *)((byte *)old_base + OLD_SECTION_H (n).sh_offset); HDRR * n_phdrr = (HDRR *)((byte *)new_base + NEW_SECTION_H (nn).sh_offset); unsigned movement = new_offsets_shift; MDEBUGADJUST (idnMax, cbDnOffset); MDEBUGADJUST (ipdMax, cbPdOffset); MDEBUGADJUST (isymMax, cbSymOffset); MDEBUGADJUST (ioptMax, cbOptOffset); MDEBUGADJUST (iauxMax, cbAuxOffset); MDEBUGADJUST (issMax, cbSsOffset); MDEBUGADJUST (issExtMax, cbSsExtOffset); MDEBUGADJUST (ifdMax, cbFdOffset); MDEBUGADJUST (crfd, cbRfdOffset); MDEBUGADJUST (iextMax, cbExtOffset); /* The Line Section, being possible off in a hole of the object, requires special handling. */ if (n_phdrr->cbLine > 0) { if (o_phdrr->cbLineOffset > (OLD_SECTION_H (n).sh_offset + OLD_SECTION_H (n).sh_size)) { /* line data is in a hole in elf. do special copy and adjust for this ld mistake. */ n_phdrr->cbLineOffset += movement; memcpy (n_phdrr->cbLineOffset + new_base, o_phdrr->cbLineOffset + old_base, n_phdrr->cbLine); } else { /* somehow line data is in .mdebug as it is supposed to be. */ MDEBUGADJUST (cbLine, cbLineOffset); } } } /* If it is the symbol table, its st_shndx field needs to be patched. */ if (NEW_SECTION_H (nn).sh_type == SHT_SYMTAB || NEW_SECTION_H (nn).sh_type == SHT_DYNSYM) { Elf32_Shdr *spt = &NEW_SECTION_H (nn); unsigned int num = spt->sh_size / spt->sh_entsize; Elf32_Sym * sym = (Elf32_Sym *) (NEW_SECTION_H (nn).sh_offset + new_base); for (; num--; sym++) { /* don't patch special section indices. */ if (sym->st_shndx == SHN_UNDEF || sym->st_shndx >= SHN_LORESERVE) continue; PATCH_INDEX (sym->st_shndx); } } } /* Close the files and make the new file executable. */ if (close (old_file)) fatal ("Can't close (%s): errno %d\n", old_name, errno); if (close (new_file)) fatal ("Can't close (%s): errno %d\n", new_name, errno); if (stat (new_name, &stat_buf) == -1) fatal ("Can't stat (%s): errno %d\n", new_name, errno); n = umask (777); umask (n); stat_buf.st_mode |= 0111 & ~n; if (chmod (new_name, stat_buf.st_mode) == -1) fatal ("Can't chmod (%s): errno %d\n", new_name, errno); }