我正在进行MOOC任务,并遇到了严重的障碍。此函数的目的是获取表示某些代码的字符串和“pad”字符串,并返回一个字符串,该字符串是输入代码的正确缩进版本,使用“pad”作为缩进。
我一直得到Valgrind错误,显然是不同的输出(他们为错误示例显示的输出与我的耸肩相同)。我已经查看了类似Valgrind错误的所有帖子,但是空洞地找出了究竟出了什么问题。下面包括函数和Valgrind错误。
C代码:
/* Indent the C-code at memory block <indent>. String <pad> represents
* one block of indentation. Only opening curly braces '{' increase the
* indentation level, and closing curly braces '}' decrease the indentation level.
* Return the pointer to the code after modification.
* Calling code is responsible of freeing only the memory block returned by
* the function.
*/
char *indent(char *input, const char *pad)
{
// First, find number of pads to add (for malloc precision)
unsigned int num_pads = 0;
unsigned int level = 0;
char *scan = input;
while (*scan) {
if (*scan == '{') {
level++;
}
if (*scan == '}') {
level -= (level) ? 1 : 0;
num_pads--;
}
if (*scan == '\n') {
num_pads += level;
}
scan++;
}
// Then, add the pads
unsigned int pad_size = strlen(pad);
unsigned int new_buffsize = strlen(input) + 1 + (num_pads * pad_size);
char *out_buff = malloc(new_buffsize + 1); // Address is 0 bytes after a block size of -- alloc'd
level = 0;
char* read_head = input;
char* write_head = out_buff;
while (*read_head) {
*write_head = *read_head; // Invalid write of size 1
if (*read_head == '{') {
level++;
}
if (*read_head == '}') {
write_head -= (level) ? pad_size : 0;
level -= (level) ? 1 : 0;
*write_head = *read_head;
}
write_head++;
if (*read_head == '\n') {
for (unsigned int i = 0; i < level; i++) {
strncpy(write_head, pad, pad_size); // Invalid write of size 1 [fixed maybe]
write_head += pad_size;
}
}
read_head++;
}
*write_head = '\0';
free(input);
return out_buff;
}
Valgrind的:
==13133== Memcheck, a memory error detector
==13133== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==13133== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
==13133== Command: ./main
==13133==
-- Original:
// This is a test file
int main(void) {
/* comment
block */
printf("juu\n");
while (1)
{
// Another comment
while (2) {
printf("jaa\n");
}
}
}
-- Comments removed:
int main(void) {
printf("juu\n");
while (1)
{
while (2) {
printf("jaa\n");
}
}
}
==13133== Invalid write of size 1
==13133== at 0x100000D4C: indent (polisher.c:205)
==13133== by 0x100000904: main (main.c:20)
==13133== Address 0x100a7d764 is 0 bytes after a block of size 132 alloc'd
==13133== at 0x100008EBB: malloc (in /usr/local/Cellar/valgrind/3.11.0/lib/valgrind/vgpreload_memcheck-amd64-darwin.so)
==13133== by 0x100000D11: indent (polisher.c:197)
==13133== by 0x100000904: main (main.c:20)
==13133==
-- After indenting:
int main(void) {
printf("juu\n");
while (1)
{
while (2) {
printf("jaa\n");
}
}
}
==13133==
==13133== HEAP SUMMARY:
==13133== in use at exit: 26,466 bytes in 190 blocks
==13133== total heap usage: 273 allocs, 83 frees, 37,049 bytes allocated
==13133==
==13133== 2,064 bytes in 1 blocks are possibly lost in loss record 56 of 62
==13133== at 0x10000917C: malloc_zone_malloc (in /usr/local/Cellar/valgrind/3.11.0/lib/valgrind/vgpreload_memcheck-amd64-darwin.so)
==13133== by 0x1004F9EFD: _objc_copyClassNamesForImage (in /usr/lib/libobjc.A.dylib)
==13133== by 0x1004ED182: protocols() (in /usr/lib/libobjc.A.dylib)
==13133== by 0x1004ED093: readClass(objc_class*, bool, bool) (in /usr/lib/libobjc.A.dylib)
==13133== by 0x1004EAC13: gc_init (in /usr/lib/libobjc.A.dylib)
==13133== by 0x1004F224E: objc_initializeClassPair_internal(objc_class*, char const*, objc_class*, objc_class*) (in /usr/lib/libobjc.A.dylib)
==13133== by 0x1004FF132: layout_string_create (in /usr/lib/libobjc.A.dylib)
==13133== by 0x1004ED83C: realizeClass(objc_class*) (in /usr/lib/libobjc.A.dylib)
==13133== by 0x1004ED300: copySwiftV1MangledName(char const*, bool) (in /usr/lib/libobjc.A.dylib)
==13133== by 0x1004ED2E9: copySwiftV1MangledName(char const*, bool) (in /usr/lib/libobjc.A.dylib)
==13133== by 0x1004ED2E9: copySwiftV1MangledName(char const*, bool) (in /usr/lib/libobjc.A.dylib)
==13133== by 0x1004ED2E9: copySwiftV1MangledName(char const*, bool) (in /usr/lib/libobjc.A.dylib)
==13133==
==13133== LEAK SUMMARY:
==13133== definitely lost: 0 bytes in 0 blocks
==13133== indirectly lost: 0 bytes in 0 blocks
==13133== possibly lost: 2,064 bytes in 1 blocks
==13133== still reachable: 0 bytes in 0 blocks
==13133== suppressed: 24,402 bytes in 189 blocks
==13133==
==13133== For counts of detected and suppressed errors, rerun with: -v
==13133== ERROR SUMMARY: 2 errors from 2 contexts (suppressed: 16 from 16)
先谢谢你一起来看看!我现在已经打了一会儿。