0a1446275
Denis Vlasenko
2008-04-20
Subject
xmalloc_open_read_close: use fstat to get file size (instead of lseek). by Joakim Tjernlund
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libbb/read.c+43 -0
| @@ -203,6 +203,48 @@ ssize_t open_read_close(const char *filename, void *buf, size_t size) | |
| return read_close(fd, buf, size); | |
| } | |
| + | // Read (potentially big) files in one go. File size is estimated by |
| + | // lseek to end. |
| + | void *xmalloc_open_read_close(const char *filename, size_t *sizep) |
| + | { |
| + | char *buf; |
| + | size_t size; |
| + | int fd; |
| + | off_t len; |
| + | struct stat st; |
| + | |
| + | fd = open(filename, O_RDONLY); |
| + | if (fd < 0) |
| + | return NULL; |
| + | |
| + | st.st_size = 0; /* in case fstat fail, define to 0 */ |
| + | fstat(fd, &st); |
| + | /* /proc/N/stat files report len 0 here */ |
| + | /* In order to make such files readable, we add small const */ |
| + | len = st.st_size | 0x3ff; /* read only 1k on unseekable files */ |
| + | size = sizep ? *sizep : INT_MAX; |
| + | if (len < size) |
| + | size = len; |
| + | buf = xmalloc(size + 1); |
| + | size = read_close(fd, buf, size); |
| + | if ((ssize_t)size < 0) { |
| + | free(buf); |
| + | return NULL; |
| + | } |
| + | xrealloc(buf, size + 1); |
| + | buf[size] = '\0'; |
| + | |
| + | if (sizep) |
| + | *sizep = size; |
| + | return buf; |
| + | } |
| + | |
| + | #ifdef USING_LSEEK_TO_GET_SIZE |
| + | /* Alternatively, file size can be obtained by lseek to the end. |
| + | * The code is slightly bigger. Retained in case fstat approach |
| + | * will not work for some weird cases (/proc, block devices, etc). |
| + | * (NB: lseek also can fail to work for some weird files) */ |
| + | |
| // Read (potentially big) files in one go. File size is estimated by | |
| // lseek to end. | |
| void *xmalloc_open_read_close(const char *filename, size_t *sizep) | |
| @@ -240,6 +282,7 @@ void *xmalloc_open_read_close(const char *filename, size_t *sizep) | |
| *sizep = size; | |
| return buf; | |
| } | |
| + | #endif |
| void *xmalloc_xopen_read_close(const char *filename, size_t *sizep) | |
| { | |