minix/lib/libexec/exec_aout.c

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2010-12-10 10:27:56 +01:00
#define _SYSTEM 1
#include <minix/type.h>
#include <minix/const.h>
#include <a.out.h>
#include <assert.h>
#include <unistd.h>
#include <errno.h>
#include <libexec.h>
int read_header_aout(
const char *exec_hdr, /* executable header */
size_t exec_len, /* executable file size */
int *sep_id, /* true iff sep I&D */
vir_bytes *text_bytes, /* place to return text size */
vir_bytes *data_bytes, /* place to return initialized data size */
vir_bytes *bss_bytes, /* place to return bss size */
phys_bytes *tot_bytes, /* place to return total size */
vir_bytes *pc, /* program entry point (initial PC) */
int *hdrlenp
)
{
/* Read the header and extract the text, data, bss and total sizes from it. */
struct exec *hdr; /* a.out header is read in here */
/* Read the header and check the magic number. The standard MINIX header
* is defined in <a.out.h>. It consists of 8 chars followed by 6 longs.
* Then come 4 more longs that are not used here.
* Byte 0: magic number 0x01
* Byte 1: magic number 0x03
* Byte 2: normal = 0x10 (not checked, 0 is OK), separate I/D = 0x20
* Byte 3: CPU type, Intel 16 bit = 0x04, Intel 32 bit = 0x10,
* Motorola = 0x0B, Sun SPARC = 0x17
* Byte 4: Header length = 0x20
* Bytes 5-7 are not used.
*
* Now come the 6 longs
* Bytes 8-11: size of text segments in bytes
* Bytes 12-15: size of initialized data segment in bytes
* Bytes 16-19: size of bss in bytes
* Bytes 20-23: program entry point
* Bytes 24-27: total memory allocated to program (text, data + stack)
* Bytes 28-31: size of symbol table in bytes
* The longs are represented in a machine dependent order,
* little-endian on the 8088, big-endian on the 68000.
* The header is followed directly by the text and data segments, and the
* symbol table (if any). The sizes are given in the header. Only the
* text and data segments are copied into memory by exec. The header is
* used here only. The symbol table is for the benefit of a debugger and
* is ignored here.
*/
assert(exec_hdr != NULL);
hdr = (struct exec *)exec_hdr;
if (exec_len < A_MINHDR) return(ENOEXEC);
/* Check magic number, cpu type, and flags. */
if (BADMAG(*hdr)) return(ENOEXEC);
#if (CHIP == INTEL && _WORD_SIZE == 2)
if (hdr->a_cpu != A_I8086) return(ENOEXEC);
#endif
#if (CHIP == INTEL && _WORD_SIZE == 4)
if (hdr->a_cpu != A_I80386) return(ENOEXEC);
#endif
if ((hdr->a_flags & ~(A_NSYM | A_EXEC | A_SEP)) != 0) return(ENOEXEC);
*sep_id = !!(hdr->a_flags & A_SEP); /* separate I & D or not */
/* Get text and data sizes. */
*text_bytes = (vir_bytes) hdr->a_text; /* text size in bytes */
*data_bytes = (vir_bytes) hdr->a_data; /* data size in bytes */
*bss_bytes = (vir_bytes) hdr->a_bss; /* bss size in bytes */
*tot_bytes = hdr->a_total; /* total bytes to allocate for prog */
if (*tot_bytes == 0) return(ENOEXEC);
if (!*sep_id) {
/* If I & D space is not separated, it is all considered data. Text=0*/
*data_bytes += *text_bytes;
*text_bytes = 0;
}
*pc = hdr->a_entry; /* initial address to start execution */
*hdrlenp = hdr->a_hdrlen & BYTE; /* header length */
return(OK);
}