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Get symbol addresses via objdump instead of libdw.
Perf is comparable to libdw. Build is much simpler.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,6 +1,3 @@ | ||
| [submodule "vendor/elfutils"] | ||
| path = vendor/elfutils | ||
| url = https://sourceware.org/git/elfutils.git | ||
| [submodule "vendor/termbox"] | ||
| path = vendor/termbox | ||
| url = https://github.com/nsf/termbox.git |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,105 @@ | ||
| #include "phpspy.h" | ||
|
|
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| static int get_php_bin_path(pid_t pid, char *path); | ||
| static int get_php_base_addr(pid_t pid, char *path, uint64_t *raddr); | ||
| static int get_symbol_offset(char *path, const char *symbol, uint64_t *raddr); | ||
| static int popen_read_line(char *buf, size_t buf_size, char *cmd_fmt, ...); | ||
|
|
||
| int get_symbol_addr(addr_memo_t *memo, pid_t pid, const char *symbol, uint64_t *raddr) { | ||
| char *php_bin_path; | ||
| uint64_t *php_base_addr; | ||
| uint64_t addr_offset; | ||
| php_bin_path = memo->php_bin_path; | ||
| php_base_addr = &memo->php_base_addr; | ||
| if (*php_bin_path == '\0' && get_php_bin_path(pid, php_bin_path) != 0) { | ||
| return 1; | ||
| } else if (*php_base_addr == 0 && get_php_base_addr(pid, php_bin_path, php_base_addr) != 0) { | ||
| return 1; | ||
| } else if (get_symbol_offset(php_bin_path, symbol, &addr_offset) != 0) { | ||
| return 1; | ||
| } | ||
| *raddr = *php_base_addr + addr_offset; | ||
| return 0; | ||
| } | ||
|
|
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| static int get_php_bin_path(pid_t pid, char *path) { | ||
| char buf[PHPSPY_STR_SIZE]; | ||
| char *cmd_fmt = "awk '/libphp7/{print $NF; exit 0} END{exit 1}' /proc/%d/maps" | ||
| " || readlink -e /proc/%d/exe"; | ||
| if (popen_read_line(buf, sizeof(buf), cmd_fmt, (int)pid, (int)pid) != 0) { | ||
| fprintf(stderr, "get_php_bin_path: Failed\n"); | ||
| return 1; | ||
| } | ||
| strcpy(path, buf); | ||
| return 0; | ||
| } | ||
|
|
||
| static int get_php_base_addr(pid_t pid, char *path, uint64_t *raddr) { | ||
| /** | ||
| * This is very likely to be incorrect/incomplete. I thought the base | ||
| * address from `/proc/<pid>/maps` + the symbol address from `readelf` would | ||
| * lead to the actual memory address, but on at least one system I tested on | ||
| * this is not the case. On that system, working backwards from the address | ||
| * printed in `gdb`, it seems the missing piece was the 'virtual address' of | ||
| * the LOAD section in ELF headers. I suspect this may have to do with | ||
| * address relocation and/or a feature called 'prelinking', but not sure. | ||
| */ | ||
| char buf[PHPSPY_STR_SIZE]; | ||
| uint64_t start_addr; | ||
| uint64_t virt_addr; | ||
| char *cmd_fmt = "grep -m1 ' %s$' /proc/%d/maps"; | ||
| if (popen_read_line(buf, sizeof(buf), cmd_fmt, path, (int)pid) != 0) { | ||
| fprintf(stderr, "get_php_base_addr: Failed to get start_addr\n"); | ||
| return 1; | ||
| } | ||
| start_addr = strtoull(buf, NULL, 16); | ||
| cmd_fmt = "objdump -p %s | awk '/LOAD/{print $5; exit}'"; | ||
| if (popen_read_line(buf, sizeof(buf), cmd_fmt, path) != 0) { | ||
| fprintf(stderr, "get_php_base_addr: Failed to get virt_addr\n"); | ||
| return 1; | ||
| } | ||
| virt_addr = strtoull(buf, NULL, 16); | ||
| *raddr = start_addr - virt_addr; | ||
| return 0; | ||
| } | ||
|
|
||
| static int get_symbol_offset(char *path, const char *symbol, uint64_t *raddr) { | ||
| char buf[PHPSPY_STR_SIZE]; | ||
| char *cmd_fmt = "objdump -Tt %s | awk '/ %s$/{print $1; exit}'"; | ||
| if (popen_read_line(buf, sizeof(buf), cmd_fmt, path, symbol) != 0) { | ||
| fprintf(stderr, "get_symbol_offset: Failed\n"); | ||
| return 1; | ||
| } | ||
| *raddr = strtoull(buf, NULL, 16); | ||
| return 0; | ||
| } | ||
|
|
||
| static int popen_read_line(char *buf, size_t buf_size, char *cmd_fmt, ...) { | ||
| FILE *fp; | ||
| char cmd[PHPSPY_STR_SIZE]; | ||
| int buf_len; | ||
| va_list cmd_args; | ||
| va_start(cmd_args, cmd_fmt); | ||
| vsprintf(cmd, cmd_fmt, cmd_args); | ||
| va_end(cmd_args); | ||
| if (!(fp = popen(cmd, "r"))) { | ||
| perror("popen"); | ||
| return 1; | ||
| } | ||
| if (fgets(buf, buf_size-1, fp) == NULL) { | ||
| fprintf(stderr, "popen_read_line: No stdout; cmd=%s\n", cmd); | ||
| pclose(fp); | ||
| return 1; | ||
| } | ||
| pclose(fp); | ||
| buf_len = strlen(buf); | ||
| while (buf_len > 0 && buf[buf_len-1] == '\n') { | ||
| --buf_len; | ||
| } | ||
| if (buf_len < 1) { | ||
| fprintf(stderr, "popen_read_line: Expected strlen(buf)>0; cmd=%s\n", cmd); | ||
| return 1; | ||
| } | ||
| buf[buf_len] = '\0'; | ||
| return 0; | ||
| } |
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Submodule elfutils
deleted from
52b6b2