tests/boot-sector: Use mkstemp() to create a unique file name

The pxe-test is run for three different targets now (x86_64, i386
and ppc64), and the bios-tables-test is run for two targets (x86_64
and i386). But each of the tests is using an invariant name for the
disk image with the boot sector code - so if the tests are running in
parallel, there is a race condition that they destroy the disk image
of a parallel test program. Let's use mkstemp() to create unique
temporary files here instead - and since mkstemp() is returning an
integer file descriptor instead of a FILE pointer, we also switch
the fwrite() and fclose() to write() and close() instead.

Reported-by: Sascha Silbe <x-qemu@se-silbe.de>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

4 files changed, 16 insertions, 9 deletions

diff --git a/tests/bios-tables-test.c b/tests/bios-tables-test.c
index 6ea2b6d00a..812f830539 100644
--- a/tests/bios-tables-test.c
+++ b/tests/bios-tables-test.c
@@ -112,7 +112,7 @@ typedef struct {
     g_assert_cmpstr(ACPI_ASSERT_CMP_str, ==, expected); \
 } while (0)
 
-static const char *disk = "tests/acpi-test-disk.raw";
+static char disk[] = "tests/acpi-test-disk-XXXXXX";
 static const char *data_dir = "tests/acpi-test-data";
 #ifdef CONFIG_IASL
 static const char *iasl = stringify(CONFIG_IASL);
diff --git a/tests/boot-sector.c b/tests/boot-sector.c
index 0168fd0247..83993143a6 100644
--- a/tests/boot-sector.c
+++ b/tests/boot-sector.c
@@ -69,12 +69,13 @@ static uint8_t boot_sector[0x7e000] = {
 };
 
 /* Create boot disk file.  */
-int boot_sector_init(const char *fname)
+int boot_sector_init(char *fname)
 {
-    FILE *f = fopen(fname, "w");
+    int fd, ret;
     size_t len = sizeof boot_sector;
 
-    if (!f) {
+    fd = mkstemp(fname);
+    if (fd < 0) {
         fprintf(stderr, "Couldn't open \"%s\": %s", fname, strerror(errno));
         return 1;
     }
@@ -86,8 +87,14 @@ int boot_sector_init(const char *fname)
                 HIGH(SIGNATURE), BOOT_SECTOR_ADDRESS + SIGNATURE_OFFSET + 1);
     }
 
-    fwrite(boot_sector, 1, len, f);
-    fclose(f);
+    ret = write(fd, boot_sector, len);
+    close(fd);
+
+    if (ret != len) {
+        fprintf(stderr, "Could not write \"%s\"", fname);
+        return 1;
+    }
+
     return 0;
 }
 
diff --git a/tests/boot-sector.h b/tests/boot-sector.h
index f64b477aa3..35d61c7e2b 100644
--- a/tests/boot-sector.h
+++ b/tests/boot-sector.h
@@ -14,8 +14,8 @@
 #ifndef TEST_BOOT_SECTOR_H
 #define TEST_BOOT_SECTOR_H
 
-/* Create boot disk file.  */
-int boot_sector_init(const char *fname);
+/* Create boot disk file. fname must be a suitable string for mkstemp() */
+int boot_sector_init(char *fname);
 
 /* Loop until signature in memory is OK.  */
 void boot_sector_test(void);
diff --git a/tests/pxe-test.c b/tests/pxe-test.c
index 5d3ddbe5e9..34282d3704 100644
--- a/tests/pxe-test.c
+++ b/tests/pxe-test.c
@@ -19,7 +19,7 @@
 
 #define NETNAME "net0"
 
-static const char *disk = "tests/pxe-test-disk.raw";
+static char disk[] = "tests/pxe-test-disk-XXXXXX";
 
 static void test_pxe_one(const char *params, bool ipv6)
 {