add open_read_close() and similar stuff
diff --git a/libbb/read.c b/libbb/read.c
new file mode 100644
index 0000000..1c2945f
--- /dev/null
+++ b/libbb/read.c
@@ -0,0 +1,133 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * Utility routines.
+ *
+ * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
+ *
+ * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
+ */
+
+#include "libbb.h"
+
+ssize_t safe_read(int fd, void *buf, size_t count)
+{
+ ssize_t n;
+
+ do {
+ n = read(fd, buf, count);
+ } while (n < 0 && errno == EINTR);
+
+ return n;
+}
+
+/*
+ * 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 cc;
+ ssize_t total;
+
+ total = 0;
+
+ while (len) {
+ cc = safe_read(fd, buf, len);
+
+ if (cc < 0)
+ 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)
+{
+ if (count) {
+ ssize_t size = full_read(fd, buf, count);
+ if (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)
+{
+ 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)
+{
+ char *p;
+
+ 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';
+ offset = (p-buffer) - size;
+ // set fd position the right after the \n
+ if (offset && lseek(fd, offset, SEEK_CUR) == (off_t)-1)
+ return NULL;
+ }
+ return buffer;
+}
+
+ssize_t read_close(int fd, void *buf, size_t size)
+{
+ int e;
+ size = full_read(fd, buf, size);
+ e = errno;
+ close(fd);
+ errno = e;
+ return size;
+}
+
+ssize_t open_read_close(const char *filename, void *buf, size_t size)
+{
+ int fd = open(filename, O_RDONLY);
+ if (fd < 0)
+ return fd;
+ return read_close(fd, buf, size);
+}
+
+void *xmalloc_open_read_close(const char *filename, size_t *sizep)
+{
+ 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 = read_close(fd, buf, size);
+ if ((ssize_t)size < 0)
+ bb_perror_msg_and_die("'%s'", filename);
+ buf[size] = '\0';
+ if (sizep) *sizep = size;
+ return buf;
+}