test code v1

tests/read_probe.c

@@ -0,0 +1,128 @@
+#define _POSIX_C_SOURCE 200809L
+
+#include <sys/types.h>
+
+#include <err.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <inttypes.h>
+#include <limits.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+static uint64_t
+parse_number(const char *text, const char *what)
+{
+	char *end;
+	uintmax_t value;
+
+	errno = 0;
+	value = strtoumax(text, &end, 0);
+	if (errno != 0 || *text == '\0' || *end != '\0' || value > INT64_MAX)
+		errx(2, "invalid %s: %s", what, text);
+	return ((uint64_t)value);
+}
+
+static void
+write_all(int fd, const unsigned char *buffer, size_t length)
+{
+	size_t done;
+	ssize_t written;
+
+	for (done = 0; done < length; done += (size_t)written) {
+		written = write(fd, buffer + done, length - done);
+		if (written < 0)
+			err(1, "write output");
+	}
+}
+
+static void
+pread_range(const char *path, uint64_t raw_offset, uint64_t raw_length,
+    const char *output)
+{
+	unsigned char buffer[65536];
+	uint64_t done;
+	ssize_t count;
+	size_t request;
+	int fd, outfd;
+
+	if (raw_length > INT64_MAX - raw_offset)
+		errx(2, "offset plus length overflows off_t");
+	fd = open(path, O_RDONLY);
+	if (fd < 0)
+		err(1, "open %s", path);
+	outfd = open(output, O_WRONLY | O_CREAT | O_TRUNC, 0600);
+	if (outfd < 0)
+		err(1, "open %s", output);
+	for (done = 0; done < raw_length; done += (uint64_t)count) {
+		request = raw_length - done < sizeof(buffer) ?
+		    (size_t)(raw_length - done) : sizeof(buffer);
+		count = pread(fd, buffer, request, (off_t)(raw_offset + done));
+		if (count < 0)
+			err(1, "pread %s at %ju", path,
+			    (uintmax_t)(raw_offset + done));
+		if (count == 0)
+			errx(1, "unexpected EOF at %ju", (uintmax_t)(raw_offset + done));
+		write_all(outfd, buffer, (size_t)count);
+	}
+	if (close(outfd) != 0 || close(fd) != 0)
+		err(1, "close");
+	printf("bytes=%ju offset=%ju\n", (uintmax_t)raw_length,
+	    (uintmax_t)raw_offset);
+}
+
+static void
+expect_error(const char *path, int expected)
+{
+	unsigned char buffer[65536];
+	ssize_t count;
+	int fd;
+
+	fd = open(path, O_RDONLY);
+	if (fd < 0) {
+		if (errno != expected)
+			errx(1, "open returned %s, expected errno %d",
+			    strerror(errno), expected);
+		printf("expected_errno=%d stage=open\n", expected);
+		return;
+	}
+	for (;;) {
+		errno = 0;
+		count = read(fd, buffer, sizeof(buffer));
+		if (count < 0)
+			break;
+		if (count == 0)
+			errx(1, "read reached EOF without expected errno %d", expected);
+	}
+	if (errno != expected)
+		errx(1, "read returned %s, expected errno %d",
+		    strerror(errno), expected);
+	if (close(fd) != 0)
+		err(1, "close");
+	printf("expected_errno=%d stage=read\n", expected);
+}
+
+int
+main(int argc, char **argv)
+{
+	uint64_t offset, length, error_number;
+
+	if (argc == 6 && strcmp(argv[1], "pread") == 0) {
+		offset = parse_number(argv[3], "offset");
+		length = parse_number(argv[4], "length");
+		pread_range(argv[2], offset, length, argv[5]);
+		return (0);
+	}
+	if (argc == 4 && strcmp(argv[1], "expect-error") == 0) {
+		error_number = parse_number(argv[3], "errno");
+		if (error_number == 0 || error_number > INT_MAX)
+			errx(2, "errno is out of range");
+		expect_error(argv[2], (int)error_number);
+		return (0);
+	}
+	errx(2, "usage: %s pread FILE OFFSET LENGTH OUTPUT | "
+	    "expect-error FILE ERRNO", argv[0]);
+}