c - 将管道文件内容传递给未知大小的 char *(动态分配)

Question

我有一个来自管道 (popen) 的 FILE *，我想将它传递给 char *artist。FILE 中的信息大小未知，因此应使用 malloc()。

FILE *tmp1;
char *artist;
tmp1 = popen("cmus-remote -Q | grep 'tag artist' | sed s/'tag artist'/''/g | sed '1s/^.//'", "r");

我该怎么做？

Answer 1

这样做的方法是使用临时缓冲区读取 block 并将它们附加到艺术家，如下所示:

char buf[8192];
char *artist = NULL;
size_t len = 0, total_len = 0;
FILE *fp;

fp = popen("cmus-remote -Q | grep 'tag artist' | sed s/'tag artist'/''/g | sed '1s/^.//'", "r");

while (!feof(fp)) {
      if ( fgets(buf, sizeof(buf), fp) == NULL ) 
             break;
      len = strlen(buf);
      artist = realloc(artist, len+1); /* +1 for \0 */
      if (artist == NULL) {
             fprintf(stderr, "Ran out of memory\n");
             exit(-1);
      }
      strncpy(artist+total_len, buf, len+1); /* concatenate the string at the end of artist */ 
      total_len += len;
}