在malloc函数中使用一个字符串的分段错误，并在另一个函数中使用它

Question

这是我的两个函数:

void base(char *str)
{
    char *without_spaces;
    without_spaces = remove_spaces(str);                                   
    printf("Without spaces length : %d n", strlen(without_spaces)); // SEGFAULT HERE !
    free(without_spaces);
}
char *remove_spaces(char *source)
{
  char *result;
  int i = 0;
  result = malloc(strlen(source) + 1);
  while (*source != 0)
  {
     if (*source != ' ') {
      result[i] = *source;
      i++;
     }
     source++;
  }
  result[i] = '';
  // If I make the printf here it's work's
  return (result);
}

下面是我如何调用基函数(字符从stdin提供)

int main()
{
  unsigned int maxsize = 324220;
  unsigned int size;
  char *str;
  char buffer[8096];
  unsigned int  i;
  unsigned int  p;
  if ((str = malloc(maxsize + 1)) == NULL)
    return (my_error(RUNTIME_ERROR_MSG, RUNTIME_ERROR_MEMORY));
  p = 0;
  while (p < maxsize && (size = read(0, buffer, 8096)) > 0)
  {
    i = 0;
    while (i < size && p < maxsize)
    {
      str[p] = buffer[i];
      i = i + 1;
      p = p + 1;
    }
  }
  str[p] = '';
  base(str);
  return (0);
}

有一个段错误，当我使用这段代码与一个非常大的str(大约500000字符)，但它的工作，当我使用它与更少的字符(如50000)。

为什么?如果我在基本函数中删除printf，并使其在删除空间函数中，就像我已经注释过它一样，它是有效的。

谢谢;)

编辑:这里是valgrind输出(编译了-g标志)

==27259== Memcheck, a memory error detector
==27259== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==27259== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
==27259== Command: ../a.out
==27259== 
Without spaces length : 324987
==27259== HEAP SUMMARY:
==27259==     in use at exit: 324,221 bytes in 1 blocks
==27259==   total heap usage: 3 allocs, 2 frees, 649,466 bytes allocated
==27259== 
==27259== LEAK SUMMARY:
==27259==    definitely lost: 324,221 bytes in 1 blocks
==27259==    indirectly lost: 0 bytes in 0 blocks
==27259==      possibly lost: 0 bytes in 0 blocks
==27259==    still reachable: 0 bytes in 0 blocks
==27259==         suppressed: 0 bytes in 0 blocks
==27259== Rerun with --leak-check=full to see details of leaked memory
==27259== 
==27259== For counts of detected and suppressed errors, rerun with: -v
==27259== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

Answer 1

我认为这些函数在逻辑上有点混乱，读取的函数也会进行复制，我更喜欢一种方法，其中有一个函数来计算malloc的良好长度，然后一个复制，最后一个从stdin读取

#include <stdlib.h>
#include <stdio.h>
static size_t   ft_strlen(const char *str)
{
    size_t      len;
    len = 0;
    while (*str != '')
    {
        if (*str != ' ')
            len++;
        str++;
    }
    return (len);
}
char            *delete_spaces(const char *str)
{
    const size_t        size = ft_strlen(str);
    char                *nospaces;
    size_t              p;
    if (!(nospaces = malloc(size + 1)))
        return (NULL);
    p = 0;
    while (*str)
    {
        if (*str != ' ')
            nospaces[p++] = *str;
        str++;
    }
    nospaces[p] = '';
    return (nospaces);
}
int             main(int ac, char **av)
{
    char    *nospaces;
    if (ac < 2)
        return (0);
    nospaces = delete_spaces(av[1]);
    printf("nospaces: %sn", nospaces);
    free(nospaces);
    return (0);
}

/a。跳出"测试带有一些空格的字符串"给出:nospaces: testingastringwithsomeesspaces

那么在这种情况下，您也将malloc正好是合适的大小(source - number of空格+ 1)

如果你使用clang编译

，你可以添加:-fsanitize =地址g3

到编译标志使用- everything -Werror在查找此类bug时，