I am modifying some http server code, and this is a function for sending file or list of directory. I keep getting this error which suggest a memory problem :
*** Error in `./a.out': free(): invalid next size (fast):
0x08b85200 ***
======= Backtrace: =========
/usr/lib/libc.so.6(+0x69923)[0xb7677923]
/usr/lib/libc.so.6(+0x6fc47)[0xb767dc47]
/usr/lib/libc.so.6(+0x70401)[0xb767e401]
./a.out[0x8049093]
./a.out[0x8049455]
./a.out[0x804952d]
./a.out[0x804964e]
/usr/lib/libc.so.6(__libc_start_main+0xf7)[0xb7626497]
./a.out[0x8048a51]
======= Memory map: ========
08048000-0804a000 r-xp 00000000 08:01 3147464 /home/baroc/Desktop/HW3/part3/a.out
0804a000-0804b000 rw-p 00001000 08:01 3147464 /home/baroc/Desktop/HW3/part3/a.out
08b85000-08ba6000 rw-p 00000000 00:00 0 [heap]
b7400000-b7421000 rw-p 00000000 00:00 0
b7421000-b7500000 ---p 00000000 00:00 0
b75df000-b75fb000 r-xp 00000000 08:01 1183170 /usr/lib/libgcc_s.so.1
b75fb000-b75fc000 rw-p 0001b000 08:01 1183170 /usr/lib/libgcc_s.so.1
b760d000-b760e000 rw-p 00000000 00:00 0
b760e000-b77c1000 r-xp 00000000 08:01 1182850 /usr/lib/libc-2.22.so
b77c1000-b77c2000 ---p 001b3000 08:01 1182850 /usr/lib/libc-2.22.so
b77c2000-b77c4000 r--p 001b3000 08:01 1182850 /usr/lib/libc-2.22.so
b77c4000-b77c5000 rw-p 001b5000 08:01 1182850 /usr/lib/libc-2.22.so
b77c5000-b77c8000 rw-p 00000000 00:00 0
b77d7000-b77d9000 rw-p 00000000 00:00 0
b77d9000-b77da000 rw-p 00000000 00:00 0
b77da000-b77dc000 r--p 00000000 00:00 0 [vvar]
b77dc000-b77dd000 r-xp 00000000 00:00 0 [vdso]
b77dd000-b77ff000 r-xp 00000000 08:01 1182848 /usr/lib/ld-2.22.so
b77ff000-b7800000 r--p 00021000 08:01 1182848 /usr/lib/ld-2.22.so
b7800000-b7801000 rw-p 00022000 08:01 1182848 /usr/lib/ld-2.22.so
bfc06000-bfc27000 rw-p 00000000 00:00 0 [stack]
Here is my code:
static int handleFileRequest(
const char *webRoot, const char *requestURI, int clntSock)
{
int statusCode;
FILE *fp = NULL;
char *file = (char *)malloc(strlen(webRoot) + strlen(requestURI) + 100);
if (file == NULL)
die("malloc failed");
strcpy(file, webRoot);
strcat(file, requestURI);
struct stat st;
if (file[strlen(file)-1] == '/') {
char *tfile = (char *)malloc(strlen(file));
strcpy(tfile, file);
strcat(tfile,"index.html");
if(stat(tfile, &st) != 0){
int fd[2];
pid_t pid;
if(pipe(fd)<0)
die("pipe() failed when list dir");
if((pid = fork())<0){
die("fork failed when list dir");
}else if(pid>0){
close(fd[0]);
if(fd[1]!=STDOUT_FILENO){
if(dup2(fd[1],STDOUT_FILENO)!=STDOUT_FILENO)
die("dup2 error to stdout");
}
close(fd[1]);
if(execl("/bin/ls", "ls", file, NULL)<0)
die("error execl ls");
close(fd[1]);
if(waitpid(pid, NULL, 0)<0){
die("waitpid error");
}
exit(0);
}else{
close(fd[1]);
int n;
char wline[DISK_IO_BUF_SIZE];
while ((n = read(fd[0], wline, sizeof(wline))) > 0) {
if (send(clntSock, wline, n, 0) != n) {
perror("\nsend() failed");
break;
}
}
close(fd[0]);
exit(0);
}
free(tfile);
goto func_end;
}else{
strcat(file, "index.html");
free(tfile);
}
}
//change this part for identifying a directory
if (stat(file, &st) == 0 && S_ISDIR(st.st_mode)) {
statusCode = 403; // "Forbidden"
sendStatusLine(clntSock, statusCode);
goto func_end;
}
fp = fopen(file, "rb");
if (fp == NULL) {
statusCode = 404; // "Not Found"
sendStatusLine(clntSock, statusCode);
goto func_end;
}
statusCode = 200; // "OK"
sendStatusLine(clntSock, statusCode);
size_t n;
char buf[DISK_IO_BUF_SIZE];
while ((n = fread(buf, 1, sizeof(buf), fp)) > 0) {
if (send(clntSock, buf, n, 0) != n) {
perror("\nsend() failed");
break;
}
}
if (ferror(fp))
perror("fread failed");
func_end:
// clean up
free(file);
if (fp)
fclose(fp);
return statusCode;
}
The problem occurs when I try to access a directory with "index.html" in it. like /test/, where has /test/index.html
It seems that the problem is with the "free(file);" at the end of the code. When I comment it out, there is no error when run on my Mac, but still error on linux. I don't understand where I did it wrong. Plz someone help me!
I used valgrind as suggested, and this is what I got:
--1936-- REDIR: 0x40ba300 (libc.so.6:malloc) redirected to 0x402a129 (malloc)
--1936-- REDIR: 0x40c0060 (libc.so.6:__GI_memchr) redirected to 0x402e100 (__GI_memchr)
--1936-- REDIR: 0x40c0d50 (libc.so.6:__GI_memcpy) redirected to 0x402ea20 (__GI_memcpy)
==1936== embedded gdbserver: reading from /tmp/vgdb-pipe-from-vgdb-to-1936-by-baroc-on-???
==1936== embedded gdbserver: writing to /tmp/vgdb-pipe-to-vgdb-from-1936-by-baroc-on-???
==1936== embedded gdbserver: shared mem /tmp/vgdb-pipe-shared-mem-vgdb-1936-by-baroc-on-???
==1936==
==1936== TO CONTROL THIS PROCESS USING vgdb (which you probably
==1936== don't want to do, unless you know exactly what you're doing,
==1936== or are doing some strange experiment):
==1936== /usr/lib/valgrind/../../bin/vgdb --pid=1936 ...command...
==1936==
==1936== TO DEBUG THIS PROCESS USING GDB: start GDB like this
==1936== /path/to/gdb ./a.out
==1936== and then give GDB the following command
==1936== target remote | /usr/lib/valgrind/../../bin/vgdb --pid=1936
==1936== --pid is optional if only one valgrind process is running
==1936==
--1936-- REDIR: 0x40be450 (libc.so.6:strcmp) redirected to 0x402555d (_vgnU_ifunc_wrapper)
--1936-- REDIR: 0x417e340 (libc.so.6:__strcmp_ssse3) redirected to 0x402de80 (strcmp)
--1936-- REDIR: 0x40beb20 (libc.so.6:strlen) redirected to 0x402555d (_vgnU_ifunc_wrapper)
--1936-- REDIR: 0x40c7c80 (libc.so.6:__strlen_sse2_bsf) redirected to 0x402cda0 (strlen)
--1936-- REDIR: 0x40bf970 (libc.so.6:strstr) redirected to 0x4031220 (strstr)
--1936-- REDIR: 0x40be510 (libc.so.6:strcpy) redirected to 0x402555d (_vgnU_ifunc_wrapper)
--1936-- REDIR: 0x40c7e50 (libc.so.6:__strcpy_ssse3) redirected to 0x402ce80 (strcpy)
--1936-- REDIR: 0x40be030 (libc.so.6:strcat) redirected to 0x402555d (_vgnU_ifunc_wrapper)
--1936-- REDIR: 0x40d3410 (libc.so.6:__strcat_ssse3) redirected to 0x402ca60 (strcat)
==1936== Invalid write of size 1
==1936== at 0x402CEC5: strcpy (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==1936== by 0x8048E63: handleFileRequest (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x804947E: doProcess (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049556: doFork (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049677: main (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== Address 0x420229a is 0 bytes after a block of size 42 alloc'd
==1936== at 0x402A1AE: malloc (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==1936== by 0x8048E4F: handleFileRequest (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x804947E: doProcess (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049556: doFork (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049677: main (in /home/baroc/Desktop/HW3/part3/a.out)
==1936==
==1936== Invalid read of size 1
==1936== at 0x8048E78: handleFileRequest (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x804947E: doProcess (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049556: doFork (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049677: main (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== Address 0x420229a is 0 bytes after a block of size 42 alloc'd
==1936== at 0x402A1AE: malloc (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==1936== by 0x8048E4F: handleFileRequest (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x804947E: doProcess (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049556: doFork (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049677: main (in /home/baroc/Desktop/HW3/part3/a.out)
==1936==
==1936== Invalid write of size 4
==1936== at 0x8048E86: handleFileRequest (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x804947E: doProcess (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049556: doFork (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049677: main (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== Address 0x420229a is 0 bytes after a block of size 42 alloc'd
==1936== at 0x402A1AE: malloc (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==1936== by 0x8048E4F: handleFileRequest (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x804947E: doProcess (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049556: doFork (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049677: main (in /home/baroc/Desktop/HW3/part3/a.out)
==1936==
==1936== Invalid write of size 4
==1936== at 0x8048E8C: handleFileRequest (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x804947E: doProcess (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049556: doFork (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049677: main (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== Address 0x420229e is 4 bytes after a block of size 42 alloc'd
==1936== at 0x402A1AE: malloc (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==1936== by 0x8048E4F: handleFileRequest (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x804947E: doProcess (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049556: doFork (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049677: main (in /home/baroc/Desktop/HW3/part3/a.out)
==1936==
==1936== Invalid write of size 2
==1936== at 0x8048E93: handleFileRequest (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x804947E: doProcess (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049556: doFork (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049677: main (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== Address 0x42022a2 is 8 bytes after a block of size 42 alloc'd
==1936== at 0x402A1AE: malloc (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==1936== by 0x8048E4F: handleFileRequest (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x804947E: doProcess (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049556: doFork (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049677: main (in /home/baroc/Desktop/HW3/part3/a.out)
==1936==
==1936== Invalid write of size 1
==1936== at 0x8048E99: handleFileRequest (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x804947E: doProcess (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049556: doFork (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049677: main (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== Address 0x42022a4 is 10 bytes after a block of size 42 alloc'd
==1936== at 0x402A1AE: malloc (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==1936== by 0x8048E4F: handleFileRequest (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x804947E: doProcess (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049556: doFork (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049677: main (in /home/baroc/Desktop/HW3/part3/a.out)
==1936==
==1936== Syscall param stat64(file_name) points to unaddressable byte(s)
==1936== at 0x411F42A: _xstat (in /usr/lib/libc-2.22.so)
==1936== by 0x804970D: stat (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8048EAB: handleFileRequest (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x804947E: doProcess (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049556: doFork (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049677: main (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== Address 0x420229a is 0 bytes after a block of size 42 alloc'd
==1936== at 0x402A1AE: malloc (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==1936== by 0x8048E4F: handleFileRequest (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x804947E: doProcess (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049556: doFork (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049677: main (in /home/baroc/Desktop/HW3/part3/a.out)
==1936==
--1936-- REDIR: 0x40ba950 (libc.so.6:free) redirected to 0x402b101 (free)
--1936-- REDIR: 0x40c2960 (libc.so.6:strchrnul) redirected to 0x4030bd0 (strchrnul)
1936 127.0.0.1 "GET /test/test2/ HTTP/1.1" 200 OK
==1936==
==1936== HEAP SUMMARY:
==1936== in use at exit: 0 bytes in 0 blocks
==1936== total heap usage: 4 allocs, 4 frees, 872 bytes allocated
==1936==
==1936== All heap blocks were freed -- no leaks are possible
==1936==
==1936== ERROR SUMMARY: 8 errors from 7 contexts (suppressed: 0 from 0)
==1936==
==1936== 1 errors in context 1 of 7:
==1936== Syscall param stat64(file_name) points to unaddressable byte(s)
==1936== at 0x411F42A: _xstat (in /usr/lib/libc-2.22.so)
==1936== by 0x804970D: stat (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8048EAB: handleFileRequest (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x804947E: doProcess (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049556: doFork (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049677: main (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== Address 0x420229a is 0 bytes after a block of size 42 alloc'd
==1936== at 0x402A1AE: malloc (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==1936== by 0x8048E4F: handleFileRequest (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x804947E: doProcess (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049556: doFork (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049677: main (in /home/baroc/Desktop/HW3/part3/a.out)
==1936==
==1936==
==1936== 1 errors in context 2 of 7:
==1936== Invalid write of size 1
==1936== at 0x8048E99: handleFileRequest (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x804947E: doProcess (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049556: doFork (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049677: main (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== Address 0x42022a4 is 10 bytes after a block of size 42 alloc'd
==1936== at 0x402A1AE: malloc (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==1936== by 0x8048E4F: handleFileRequest (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x804947E: doProcess (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049556: doFork (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049677: main (in /home/baroc/Desktop/HW3/part3/a.out)
==1936==
==1936==
==1936== 1 errors in context 3 of 7:
==1936== Invalid write of size 4
==1936== at 0x8048E8C: handleFileRequest (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x804947E: doProcess (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049556: doFork (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049677: main (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== Address 0x420229e is 4 bytes after a block of size 42 alloc'd
==1936== at 0x402A1AE: malloc (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==1936== by 0x8048E4F: handleFileRequest (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x804947E: doProcess (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049556: doFork (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049677: main (in /home/baroc/Desktop/HW3/part3/a.out)
==1936==
==1936==
==1936== 1 errors in context 4 of 7:
==1936== Invalid write of size 4
==1936== at 0x8048E86: handleFileRequest (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x804947E: doProcess (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049556: doFork (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049677: main (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== Address 0x420229a is 0 bytes after a block of size 42 alloc'd
==1936== at 0x402A1AE: malloc (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==1936== by 0x8048E4F: handleFileRequest (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x804947E: doProcess (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049556: doFork (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049677: main (in /home/baroc/Desktop/HW3/part3/a.out)
==1936==
==1936==
==1936== 1 errors in context 5 of 7:
==1936== Invalid read of size 1
==1936== at 0x8048E78: handleFileRequest (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x804947E: doProcess (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049556: doFork (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049677: main (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== Address 0x420229a is 0 bytes after a block of size 42 alloc'd
==1936== at 0x402A1AE: malloc (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==1936== by 0x8048E4F: handleFileRequest (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x804947E: doProcess (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049556: doFork (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049677: main (in /home/baroc/Desktop/HW3/part3/a.out)
==1936==
==1936==
==1936== 1 errors in context 6 of 7:
==1936== Invalid write of size 1
==1936== at 0x402CEC5: strcpy (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==1936== by 0x8048E63: handleFileRequest (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x804947E: doProcess (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049556: doFork (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049677: main (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== Address 0x420229a is 0 bytes after a block of size 42 alloc'd
==1936== at 0x402A1AE: malloc (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==1936== by 0x8048E4F: handleFileRequest (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x804947E: doProcess (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049556: doFork (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049677: main (in /home/baroc/Desktop/HW3/part3/a.out)
==1936==
==1936==
==1936== 2 errors in context 7 of 7:
==1936== Invalid write of size 2
==1936== at 0x8048E93: handleFileRequest (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x804947E: doProcess (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049556: doFork (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049677: main (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== Address 0x42022a2 is 8 bytes after a block of size 42 alloc'd
==1936== at 0x402A1AE: malloc (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==1936== by 0x8048E4F: handleFileRequest (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x804947E: doProcess (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049556: doFork (in /home/baroc/Desktop/HW3/part3/a.out)
==1936== by 0x8049677: main (in /home/baroc/Desktop/HW3/part3/a.out)
==1936==
==1936== ERROR SUMMARY: 8 errors from 7 contexts (suppressed: 0 from 0)
