最不值得一提的BUG

第1個(gè)4小時(shí)：縮小排查范圍，是什么引起段錯(cuò)誤

TickStatusIO():105ti_ck_mutil():266Segmentation fault (core dumped) (gdb) bt#0  0x401b28e0 in vfwprintf () from /lib/libc.so.6#1  0x00009d10 in ti_ck_mutil (cmdstr=0xbebffa4c, len=1) at src/ti.c:268#2  0x00008e2c in TickStatusIO () at src/initgpio.c:106#3  0x00009238 in main (argc=1, argv=0xbebffbf4) at src/initgpio.c:304

int ti_ck_mutil(char *cmdstr, int count){ FILE *stream; char strout[256]; int ret, failcount = 0;  for (int i = 0; i < count; i++) { printf("%s()%d\n", __FUNCTION__, __LINE__);//226行 stream = popen(cmdstr, "r");//未檢查文件是否成功 ret = fread(strout, sizeof(char), sizeof(strout), stream); // 228行  strout[ret] = '\0'; pclose(stream); // ... } return failcount;}

fread輸入?yún)?shù)只有4個(gè)，猜測(cè)可能存在的失敗原因有3點(diǎn)：

#0  0x000028e0 in ?? () #1  0x000038e8 in ?? () #2  0x000048ec in ?? () #3  0x000068e0 in ?? () #4  0x00009d10 in ti_ck_mutil (cmdstr=0xbebffa4c, len=1) at src/ti.c:268#5  0x00008e2c in TickStatusIO () at src/initgpio.c:106#6  0x00009238 in main (argc=1, argv=0xbebffbf4) at src/initgpio.c:304

第2個(gè)4小時(shí)：是內(nèi)存越界？還是資源不足？

stream = popen(cmdstr, "r");ret = fread(strout, sizeof(char), sizeof(strout), stream); 修改后 stream = popen(cmdstr, "r");if (stream == 0) { perror("popen error:");}ret = fread(strout, sizeof(char), sizeof(strout) - 1, stream);

	

		
		

			
		

	

popen error:: Too many open files

機(jī)理分析：為什么文件打開(kāi)太多？

RETURN VALUEThe popen() function returns NULL if the fork(2) or pipe(2) calls fail, or if it cannot allocate memory.

ERRORSThe popen() function does not set errno if memory allocation fails. If the underlying fork(2) or pipe(2) fails, errno is set appropriately. If the type argument is invalid, and this condition is detected, errno is set to EINVAL.

watch -n 1 ls -l /proc/PID/fd