fs: handle an interrupted read("all")

lib/fs.c

@@ -197,6 +197,7 @@ uc_fs_read_common(uc_vm_t *vm, size_t nargs, FILE **fp)
 	const char *lstr;
 	int64_t lsize;
 	ssize_t llen;
+	int err;
 
 	if (!fp || !*fp)
 		err_return(EBADF);
@@ -216,23 +217,44 @@ uc_fs_read_common(uc_vm_t *vm, size_t nargs, FILE **fp)
 			len = (size_t)llen;
 		}
 		else if (llen == 3 && !strcmp(lstr, "all")) {
+			clearerr(*fp);
+
 			while (true) {
+				errno = 0;
 				rlen = fread(buf, 1, sizeof(buf), *fp);
+				err = errno;
+
+				if (rlen > 0) {
+					tmp = realloc(p, len + rlen);
 
-				tmp = realloc(p, len + rlen);
+					if (!tmp) {
+						free(p);
+						err_return(ENOMEM);
+					}
 
-				if (!tmp) {
-					free(p);
-					err_return(ENOMEM);
+					memcpy(tmp + len, buf, rlen);
+
+					p = tmp;
+					len += rlen;
 				}
 
-				memcpy(tmp + len, buf, rlen);
+				if (rlen == sizeof(buf))
+					continue;
 
-				p = tmp;
-				len += rlen;
+				/* no error means EOF */
+				if (!ferror(*fp))
+					break;
 
-				if (rlen == 0)
+				clearerr(*fp);
+
+				if (err == EINTR)
+					continue;
+
+				if (err == EAGAIN || err == EWOULDBLOCK)
 					break;
+
+				free(p);
+				err_return(err ? err : EIO);
 			}
 		}
 		else if (llen == 1) {

tests/custom/06_lib_uloop/14_read_all_eintr

@@ -0,0 +1,33 @@
+read("all") retries a read that a signal interrupted instead of treating it
+as end of file, whether or not data arrived before the interruption.
+
+libubox installs its SIGCHLD handler without SA_RESTART, so in a uloop based
+host (rpcd, uhttpd, ...) any child exiting while the VM is blocked in a read
+interrupts that read with EINTR.
+
+-- Testcase --
+{%
+	import * as uloop from 'uloop';
+	import { popen, error } from 'fs';
+
+	uloop.init();
+
+	// An unrelated child that exits while we are blocked reading
+	let other = popen('sleep 1', 'r');
+
+	let proc = popen('sleep 2; echo payload', 'r');
+
+	let data = proc.read('all');
+
+	printf('data: %J\nerror: %J\nexit: %d\n', data, error(), proc.close());
+
+	other.close();
+	uloop.done();
+%}
+-- End --
+
+-- Expect stdout --
+data: "payload\n"
+error: null
+exit: 0
+-- End --

tests/custom/99_bugs/64_fs_read_all_error

@@ -0,0 +1,17 @@
+read("all") reports a read error as null plus fs.error() instead of
+returning an empty string as if it had reached end of file.
+
+-- Testcase --
+{%
+	import { open, error } from 'fs';
+
+	let fp = open('/', 'r');
+
+	printf('data: %J\nerror: %J\n', fp.read('all'), error());
+%}
+-- End --
+
+-- Expect stdout --
+data: null
+error: "Is a directory"
+-- End --