Syscall 参数 getcwd（buf）指向不可寻址的字节-解网

问：

我是第一次使用 valgrind 测试程序。我没有找到有关此错误的任何帮助。我做错了什么？我该如何解决？

最小可重复示例：

#include <sys/stat.h>
#include <stdio.h>
#include <stdlib.h>


int main(){
   char* dir = "testdir";
   mkdir(dir,0777);
   char* buf = calloc(1, sizeof(char)*255);
   char* directory = realpath(dir, buf);
   printf("%s\n", directory);
   free(buf);
}

valgrind 报告：

==18518== Syscall param getcwd(buf) points to unaddressable byte(s)
==18518==    at 0x4969AF2: getcwd (getcwd.c:78)
==18518==    by 0x48AD520: realpath@@GLIBC_2.3 (canonicalize.c:88)
==18518==    by 0x109216: main (in /home/sol/Documents/SOLProject/.test/a.out)
==18518==  Address 0x4a5013f is 0 bytes after a block of size 255 alloc'd
==18518==    at 0x483DD99: calloc (in /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so)
==18518==    by 0x1091FF: main (in /home/sol/Documents/SOLProject/.test/a.out)
==18518== 
/home/sol/Documents/SOLProject/.test/testdir
==18518== 
==18518== HEAP SUMMARY:
==18518==     in use at exit: 0 bytes in 0 blocks
==18518==   total heap usage: 2 allocs, 2 frees, 1,279 bytes allocated
==18518== 
==18518== All heap blocks were freed -- no leaks are possible
==18518== 
==18518== For lists of detected and suppressed errors, rerun with: -s
==18518== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)

C 马洛克 ·瓦尔格林德 getcwd

@gregspears 您强调的是尝试修改与字符串文字关联的内存时出现的未定义行为，这不是问题中存在的问题。如果字符串文本的类型是，则使用 a 指向字符串文本是完全有效的。因此，虽然不应该做任何事情，并且在此程序中是等效的，但限定数据（如）将更好地显示意图，并在您尝试修改所述数据时发出警告。char *char [N]char *dirchar dir[]constconst char *dir

答：

1赞 Paul Floyd 11/1/2023 #1

在 FreeBSD 13.2 上使用热的 valgrind 3.22 我得到

==12420== Syscall param __realpathat(buf) points to unaddressable byte(s)
==12420==    at 0x4994B1A: ??? (in /lib/libc.so.7)
==12420==    by 0x49CDC16: realpath (in /lib/libc.so.7)
==12420==    by 0x2019D3: main (so12.c:10)
==12420==  Address 0x545f13f is 0 bytes after a block of size 255 alloc'd
==12420==    at 0x4851725: calloc (vg_replace_malloc.c:1599)
==12420==    by 0x2019C2: main (so12.c:9)

正如评论中提到的，期望realpath

The resolved_path argument must point to a buffer capable of storing at
least PATH_MAX characters, or be NULL.

如果我更改为将 NULL 作为缓冲区realpath

#include <sys/stat.h>
#include <stdio.h>
#include <stdlib.h>


int main(){
   char* dir = "testdir";
   mkdir(dir,0777);
   char* directory = realpath(dir, NULL);
   printf("%s\n", directory);
   free(directory);
}

然后我没有错误。

上一个：如何在Yacc（Linux Bison）中显式指定EOF？

下一个：C++ 头文件更改程序中断

Syscall 参数 getcwd（buf） 指向不可寻址的字节

Syscall param getcwd(buf) points to unaddressable byte(s)

评论

Syscall 参数 getcwd（buf）指向不可寻址的字节