/*
* swap.c
*/
extern int buf[];
int* bufp0 = &buf[0];
static int* bufp1;
static void incr() {
static int count=0;
count++;
}
void swap() {
int temp;
incr();
bufp1 = &buf[1];
temp = *bufp0;
*bufp0 = *bufp1;
*bufp1 = temp;
}
| in .symtab? | type | module | section | |
|---|---|---|---|---|
| buf | Yes | external | m | .data |
| bufp0 | Yes | global | swap | .data |
| bufp1 | Yes | local | swap | .bss |
| swap | Yes | global | swap | .text |
| temp | No | —— | —– | —— |
| incr | Yes | local | swap | .text |
| count | Yes | local | swap | .bss |
(cd ./site/content/chapter7/code/7.6; make && make sym)
output:
gcc -c swap.c
objdump -t swap.o
swap.o： 文件格式 elf64-x86-64
SYMBOL TABLE:
0000000000000000 l O .bss 0000000000000008 bufp1
0000000000000000 l F .text 0000000000000015 incr
0000000000000008 l O .bss 0000000000000004 count.1747
0000000000000000 g O .data 0000000000000008 bufp0
0000000000000000 *UND* 0000000000000000 buf
0000000000000015 g F .text 0000000000000049 swap