*/
#include "libbb.h"
+#if ENABLE_FEATURE_MODPROBE_SMALL_ZIPPED
+#include "unarchive.h"
+#endif
-ssize_t safe_read(int fd, void *buf, size_t count)
+ssize_t FAST_FUNC safe_read(int fd, void *buf, size_t count)
{
ssize_t n;
return n;
}
+/* Suppose that you are a shell. You start child processes.
+ * They work and eventually exit. You want to get user input.
+ * You read stdin. But what happens if last child switched
+ * its stdin into O_NONBLOCK mode?
+ *
+ * *** SURPRISE! It will affect the parent too! ***
+ * *** BIG SURPRISE! It stays even after child exits! ***
+ *
+ * This is a design bug in UNIX API.
+ * fcntl(0, F_SETFL, fcntl(0, F_GETFL, 0) | O_NONBLOCK);
+ * will set nonblocking mode not only on _your_ stdin, but
+ * also on stdin of your parent, etc.
+ *
+ * In general,
+ * fd2 = dup(fd1);
+ * fcntl(fd2, F_SETFL, fcntl(fd2, F_GETFL, 0) | O_NONBLOCK);
+ * sets both fd1 and fd2 to O_NONBLOCK. This includes cases
+ * where duping is done implicitly by fork() etc.
+ *
+ * We need
+ * fcntl(fd2, F_SETFD, fcntl(fd2, F_GETFD, 0) | O_NONBLOCK);
+ * (note SETFD, not SETFL!) but such thing doesn't exist.
+ *
+ * Alternatively, we need nonblocking_read(fd, ...) which doesn't
+ * require O_NONBLOCK dance at all. Actually, it exists:
+ * n = recv(fd, buf, len, MSG_DONTWAIT);
+ * "MSG_DONTWAIT:
+ * Enables non-blocking operation; if the operation
+ * would block, EAGAIN is returned."
+ * but recv() works only for sockets!
+ *
+ * So far I don't see any good solution, I can only propose
+ * that affected readers should be careful and use this routine,
+ * which detects EAGAIN and uses poll() to wait on the fd.
+ * Thankfully, poll() doesn't care about O_NONBLOCK flag.
+ */
+ssize_t FAST_FUNC nonblock_safe_read(int fd, void *buf, size_t count)
+{
+ struct pollfd pfd[1];
+ ssize_t n;
+
+ while (1) {
+ n = safe_read(fd, buf, count);
+ if (n >= 0 || errno != EAGAIN)
+ return n;
+ /* fd is in O_NONBLOCK mode. Wait using poll and repeat */
+ pfd[0].fd = fd;
+ pfd[0].events = POLLIN;
+ safe_poll(pfd, 1, -1);
+ }
+}
+
/*
* Read all of the supplied buffer from a file.
* This does multiple reads as necessary.
* Returns the amount read, or -1 on an error.
* A short read is returned on an end of file.
*/
-ssize_t full_read(int fd, void *buf, size_t len)
+ssize_t FAST_FUNC full_read(int fd, void *buf, size_t len)
{
ssize_t cc;
ssize_t total;
while (len) {
cc = safe_read(fd, buf, len);
- if (cc < 0)
- return cc; /* read() returns -1 on failure. */
-
+ if (cc < 0) {
+ if (total) {
+ /* we already have some! */
+ /* user can do another read to know the error code */
+ return total;
+ }
+ return cc; /* read() returns -1 on failure. */
+ }
if (cc == 0)
break;
-
buf = ((char *)buf) + cc;
total += cc;
len -= cc;
return total;
}
-// Die with an error message if we can't read the entire buffer.
-void xread(int fd, void *buf, size_t count)
+/* Die with an error message if we can't read the entire buffer. */
+void FAST_FUNC xread(int fd, void *buf, size_t count)
{
if (count) {
ssize_t size = full_read(fd, buf, count);
- if (size != count)
+ if ((size_t)size != count)
bb_error_msg_and_die("short read");
}
}
-// Die with an error message if we can't read one character.
-unsigned char xread_char(int fd)
+/* Die with an error message if we can't read one character. */
+unsigned char FAST_FUNC xread_char(int fd)
{
char tmp;
-
xread(fd, &tmp, 1);
-
return tmp;
}
-// Read one line a-la fgets. Works only on seekable streams
-char *reads(int fd, char *buffer, size_t size)
+// Reads one line a-la fgets (but doesn't save terminating '\n').
+// Reads byte-by-byte. Useful when it is important to not read ahead.
+// Bytes are appended to pfx (which must be malloced, or NULL).
+char* FAST_FUNC xmalloc_reads(int fd, char *buf, size_t *maxsz_p)
{
char *p;
+ size_t sz = buf ? strlen(buf) : 0;
+ size_t maxsz = maxsz_p ? *maxsz_p : MAXINT(size_t);
- if (size < 2)
- return NULL;
- size = full_read(fd, buffer, size-1);
- if ((ssize_t)size <= 0)
- return NULL;
-
- buffer[size] = '\0';
- p = strchr(buffer, '\n');
- if (p) {
- off_t offset;
- *p++ = '\0';
- // avoid incorrect (unsigned) widening
- offset = (off_t)(p-buffer) - (off_t)size;
- // set fd position the right after the \n
- if (offset && lseek(fd, offset, SEEK_CUR) == (off_t)-1)
- return NULL;
+ goto jump_in;
+ while (sz < maxsz) {
+ if ((size_t)(p - buf) == sz) {
+ jump_in:
+ buf = xrealloc(buf, sz + 128);
+ p = buf + sz;
+ sz += 128;
+ }
+ /* nonblock_safe_read() because we are used by e.g. shells */
+ if (nonblock_safe_read(fd, p, 1) != 1) { /* EOF/error */
+ if (p == buf) { /* we read nothing */
+ free(buf);
+ return NULL;
+ }
+ break;
+ }
+ if (*p == '\n')
+ break;
+ p++;
}
- return buffer;
+ *p = '\0';
+ if (maxsz_p)
+ *maxsz_p = p - buf;
+ p++;
+ return xrealloc(buf, p - buf);
}
-ssize_t read_close(int fd, void *buf, size_t size)
+ssize_t FAST_FUNC read_close(int fd, void *buf, size_t size)
{
- int e;
+ /*int e;*/
size = full_read(fd, buf, size);
- e = errno;
+ /*e = errno;*/
close(fd);
- errno = e;
+ /*errno = e;*/
return size;
}
-ssize_t open_read_close(const char *filename, void *buf, size_t size)
+ssize_t FAST_FUNC open_read_close(const char *filename, void *buf, size_t size)
{
int fd = open(filename, O_RDONLY);
if (fd < 0)
return read_close(fd, buf, size);
}
-void *xmalloc_open_read_close(const char *filename, size_t *sizep)
+
+// Read (potentially big) files in one go. File size is estimated
+// by stat. Extra '\0' byte is appended.
+void* FAST_FUNC xmalloc_read(int fd, size_t *maxsz_p)
{
char *buf;
- size_t size = sizep ? *sizep : INT_MAX;
- int fd = xopen(filename, O_RDONLY);
- off_t len = xlseek(fd, 0, SEEK_END);
- xlseek(fd, 0, SEEK_SET);
-
- if (len > size)
- bb_error_msg_and_die("file '%s' is too big", filename);
- size = len;
- buf = xmalloc(size+1);
+ size_t size, rd_size, total;
+ size_t to_read;
+ struct stat st;
+
+ to_read = maxsz_p ? *maxsz_p : MAXINT(ssize_t); /* max to read */
+
+ /* Estimate file size */
+ st.st_size = 0; /* in case fstat fails, assume 0 */
+ fstat(fd, &st);
+ /* /proc/N/stat files report st_size 0 */
+ /* In order to make such files readable, we add small const */
+ size = (st.st_size | 0x3ff) + 1;
+
+ total = 0;
+ buf = NULL;
+ while (1) {
+ if (to_read < size)
+ size = to_read;
+ buf = xrealloc(buf, total + size + 1);
+ rd_size = full_read(fd, buf + total, size);
+ if ((ssize_t)rd_size == (ssize_t)(-1)) { /* error */
+ free(buf);
+ return NULL;
+ }
+ total += rd_size;
+ if (rd_size < size) /* EOF */
+ break;
+ if (to_read <= rd_size)
+ break;
+ to_read -= rd_size;
+ /* grow by 1/8, but in [1k..64k] bounds */
+ size = ((total / 8) | 0x3ff) + 1;
+ if (size > 64*1024)
+ size = 64*1024;
+ }
+ xrealloc(buf, total + 1);
+ buf[total] = '\0';
+
+ if (maxsz_p)
+ *maxsz_p = total;
+ 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* FAST_FUNC xmalloc_open_read_close(const char *filename, size_t *maxsz_p)
+{
+ char *buf;
+ size_t size;
+ int fd;
+ off_t len;
+
+ fd = open(filename, O_RDONLY);
+ if (fd < 0)
+ return NULL;
+
+ /* /proc/N/stat files report len 0 here */
+ /* In order to make such files readable, we add small const */
+ size = 0x3ff; /* read only 1k on unseekable files */
+ len = lseek(fd, 0, SEEK_END) | 0x3ff; /* + up to 1k */
+ if (len != (off_t)-1) {
+ xlseek(fd, 0, SEEK_SET);
+ size = maxsz_p ? *maxsz_p : INT_MAX;
+ if (len < size)
+ size = len;
+ }
+
+ buf = xmalloc(size + 1);
size = read_close(fd, buf, size);
- if ((ssize_t)size < 0)
- bb_perror_msg_and_die("'%s'", filename);
+ if ((ssize_t)size < 0) {
+ free(buf);
+ return NULL;
+ }
+ xrealloc(buf, size + 1);
buf[size] = '\0';
- if (sizep) *sizep = size;
+
+ if (maxsz_p)
+ *maxsz_p = size;
+ return buf;
+}
+#endif
+
+// Read (potentially big) files in one go. File size is estimated
+// by stat.
+void* FAST_FUNC xmalloc_open_read_close(const char *filename, size_t *maxsz_p)
+{
+ char *buf;
+ int fd;
+
+ fd = open(filename, O_RDONLY);
+ if (fd < 0)
+ return NULL;
+
+ buf = xmalloc_read(fd, maxsz_p);
+ close(fd);
return buf;
}
+
+void* FAST_FUNC xmalloc_xopen_read_close(const char *filename, size_t *maxsz_p)
+{
+ void *buf = xmalloc_open_read_close(filename, maxsz_p);
+ if (!buf)
+ bb_perror_msg_and_die("can't read '%s'", filename);
+ return buf;
+}
+
+#if ENABLE_FEATURE_MODPROBE_SMALL_ZIPPED
+void* FAST_FUNC xmalloc_open_zipped_read_close(const char *fname, size_t *maxsz_p)
+{
+ char *image;
+ char *suffix;
+
+ int fd = open(fname, O_RDONLY);
+ if (fd < 0)
+ return NULL;
+
+ suffix = strrchr(fname, '.');
+ if (suffix) {
+ if (strcmp(suffix, ".gz") == 0)
+ open_transformer(fd, unpack_gz_stream, "gunzip");
+ else if (strcmp(suffix, ".bz2") == 0)
+ open_transformer(fd, unpack_bz2_stream, "bunzip2");
+ }
+
+ image = xmalloc_read(fd, maxsz_p);
+ if (!image)
+ bb_perror_msg("read error from '%s'", fname);
+ close(fd);
+
+ return image;
+}
+#endif
projects / oweals / busybox.git / blobdiff