Use Malloc for path's buffers instead of stack

ChangeLog

@@ -2,6 +2,8 @@
 
 	This release:
 	- Significantly reduces the libpmem's stack usage.
+	- Decrease stack usage by allocating paths' buffers on heap
+
 
 Tue Aug 8 2023 Oksana Sałyk <[email protected]>
 

src/core/out.c

@@ -161,7 +161,7 @@ out_init(const char *log_prefix, const char *log_level_var,
 				log_file[0] != '\0') {
 
 		/* reserve more than enough space for a PID + '\0' */
-		char log_file_pid[PATH_MAX];
+		static char log_file_pid[PATH_MAX];
 		size_t len = strlen(log_file);
 		if (len > 0 && log_file[len - 1] == '-') {
 			if (util_snprintf(log_file_pid, PATH_MAX, "%s%d",

src/libpmem2/auto_flush_linux.c

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: BSD-3-Clause
-/* Copyright 2018-2020, Intel Corporation */
+/* Copyright 2018-2023, Intel Corporation */
 
 /*
  * auto_flush_linux.c -- Linux auto flush detection
@@ -16,6 +16,7 @@
 #include "os.h"
 #include "fs.h"
 #include "auto_flush.h"
+#include "alloc.h"
 
 #define BUS_DEVICE_PATH "/sys/bus/nd/devices"
 #define PERSISTENCE_DOMAIN "persistence_domain"
@@ -87,9 +88,16 @@ check_domain_in_region(const char *region_path)
 
 	struct fs *reg = NULL;
 	struct fs_entry *reg_entry;
-	char domain_path[PATH_MAX];
+	char *domain_path = NULL;
 	int cpu_cache = 0;
 
+	domain_path = Malloc(PATH_MAX * sizeof(char));
+	if (domain_path == NULL) {
+		ERR("!Malloc");
+		cpu_cache = -1;
+		goto end;
+	}
+
 	reg = fs_new(region_path);
 	if (reg == NULL) {
 		ERR("!fs_new: \"%s\"", region_path);
@@ -122,6 +130,8 @@ check_domain_in_region(const char *region_path)
 end:
 	if (reg)
 		fs_delete(reg);
+	if (domain_path)
+		Free(domain_path);
 	return cpu_cache;
 }
 

src/libpmem2/deep_flush_linux.c

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: BSD-3-Clause
-/* Copyright 2020, Intel Corporation */
+/* Copyright 2020-2023, Intel Corporation */
 
 /*
  * deep_flush_linux.c -- deep_flush functionality
@@ -18,6 +18,7 @@
 #include "persist.h"
 #include "pmem2_utils.h"
 #include "region_namespace.h"
+#include "alloc.h"
 
 /*
  * pmem2_deep_flush_write -- perform write to deep_flush file
@@ -28,19 +29,28 @@ pmem2_deep_flush_write(unsigned region_id)
 {
 	LOG(3, "region_id %d", region_id);
 
-	char deep_flush_path[PATH_MAX];
-	int deep_flush_fd;
+	int ret = 0;
+	char *deep_flush_path = NULL;
+	int deep_flush_fd = -1;
 	char rbuf[2];
 
+	deep_flush_path = Malloc(PATH_MAX * sizeof(char));
+	if (deep_flush_path == NULL) {
+		ERR("!Malloc");
+		ret = PMEM2_E_ERRNO;
+		goto end;
+	}
+
 	if (util_snprintf(deep_flush_path, PATH_MAX,
 		"/sys/bus/nd/devices/region%u/deep_flush", region_id) < 0) {
 		ERR("!snprintf");
-		return PMEM2_E_ERRNO;
+		ret = PMEM2_E_ERRNO;
+		goto end;
 	}
 
 	if ((deep_flush_fd = os_open(deep_flush_path, O_RDONLY)) < 0) {
 		LOG(1, "!os_open(\"%s\", O_RDONLY)", deep_flush_path);
-		return 0;
+		goto end;
 	}
 
 	if (read(deep_flush_fd, rbuf, sizeof(rbuf)) != 2) {
@@ -54,11 +64,12 @@ pmem2_deep_flush_write(unsigned region_id)
 	}
 
 	os_close(deep_flush_fd);
+	deep_flush_fd = -1;
 
 	if ((deep_flush_fd = os_open(deep_flush_path, O_WRONLY)) < 0) {
 		LOG(1, "Cannot open deep_flush file %s to write",
 			deep_flush_path);
-		return 0;
+		goto end;
 	}
 
 	if (write(deep_flush_fd, "1", 1) != 1) {
@@ -67,8 +78,11 @@ pmem2_deep_flush_write(unsigned region_id)
 	}
 
 end:
-	os_close(deep_flush_fd);
-	return 0;
+	if (deep_flush_fd > -1)
+		os_close(deep_flush_fd);
+	if (deep_flush_path)
+		Free(deep_flush_path);
+	return ret;
 }
 
 /*

src/libpmem2/pmem2_utils_linux.c

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: BSD-3-Clause
-/* Copyright 2014-2020, Intel Corporation */
+/* Copyright 2014-2023, Intel Corporation */
 
 #include <errno.h>
 #include <fcntl.h>
@@ -14,6 +14,7 @@
 #include "pmem2_utils.h"
 #include "region_namespace.h"
 #include "source.h"
+#include "alloc.h"
 
 /*
  * pmem2_get_type_from_stat -- determine type of file based on output of stat
@@ -37,34 +38,58 @@ pmem2_get_type_from_stat(const os_stat_t *st, enum pmem2_file_type *type)
 		return PMEM2_E_INVALID_FILE_TYPE;
 	}
 
-	char spath[PATH_MAX];
-	int ret = util_snprintf(spath, PATH_MAX,
+	int ret = 0;
+	char *spath = NULL;
+	char *npath = NULL;
+
+	spath = Malloc(PATH_MAX * sizeof(char));
+	if (spath == NULL) {
+		ERR("!Malloc");
+		return PMEM2_E_ERRNO;
+	}
+
+	ret = util_snprintf(spath, PATH_MAX,
 			"/sys/dev/char/%u:%u/subsystem",
 			os_major(st->st_rdev), os_minor(st->st_rdev));
 
 	if (ret < 0) {
 		/* impossible */
 		ERR("!snprintf");
 		ASSERTinfo(0, "snprintf failed");
-		return PMEM2_E_ERRNO;
+		ret = PMEM2_E_ERRNO;
+		goto end;
 	}
 
 	LOG(4, "device subsystem path \"%s\"", spath);
 
-	char npath[PATH_MAX];
+	npath = Malloc(PATH_MAX * sizeof(char));
+	if (npath == NULL) {
+		ERR("!Malloc");
+		ret = PMEM2_E_ERRNO;
+		goto end;
+	}
+
 	char *rpath = realpath(spath, npath);
 	if (rpath == NULL) {
 		ERR("!realpath \"%s\"", spath);
-		return PMEM2_E_ERRNO;
+		ret = PMEM2_E_ERRNO;
+		goto end;
 	}
 
 	char *basename = strrchr(rpath, '/');
 	if (!basename || strcmp("dax", basename + 1) != 0) {
 		LOG(3, "%s path does not match device dax prefix path", rpath);
-		return PMEM2_E_INVALID_FILE_TYPE;
+		ret = PMEM2_E_INVALID_FILE_TYPE;
+		goto end;
 	}
 
 	*type = PMEM2_FTYPE_DEVDAX;
 
-	return 0;
+end:
+	if (npath)
+		Free(npath);
+	if (spath)
+		Free(spath);
+
+	return ret;
 }

src/libpmem2/region_namespace_ndctl.c

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: BSD-3-Clause
-/* Copyright 2020-2022, Intel Corporation */
+/* Copyright 2020-2023, Intel Corporation */
 
 /*
  * region_namespace_ndctl.c -- common ndctl functions
@@ -16,6 +16,7 @@
 #include "region_namespace_ndctl.h"
 #include "region_namespace.h"
 #include "out.h"
+#include "alloc.h"
 
 /*
  * ndctl_match_devdax -- (internal) returns 0 if the devdax matches
@@ -27,30 +28,43 @@ ndctl_match_devdax(dev_t st_rdev, const char *devname)
 {
 	LOG(3, "st_rdev %lu devname %s", st_rdev, devname);
 
+	int ret = 0;
+	char *path;
+	os_stat_t stat;
+
 	if (*devname == '\0')
 		return 1;
 
-	char path[PATH_MAX];
-	os_stat_t stat;
+	path = Malloc(PATH_MAX * sizeof(char));
+	if (path == NULL) {
+		ERR("!Malloc");
+		return PMEM2_E_ERRNO;
+	}
 
 	if (util_snprintf(path, PATH_MAX, "/dev/%s", devname) < 0) {
 		ERR("!snprintf");
-		return PMEM2_E_ERRNO;
+		ret = PMEM2_E_ERRNO;
+		goto end;
 	}
 
 	if (os_stat(path, &stat)) {
 		ERR("!stat %s", path);
-		return PMEM2_E_ERRNO;
+		ret = PMEM2_E_ERRNO;
+		goto end;
 	}
 
 	if (st_rdev != stat.st_rdev) {
 		LOG(10, "skipping not matching device: %s", path);
-		return 1;
+		ret = 1;
+		goto end;
 	}
 
 	LOG(4, "found matching device: %s", path);
 
-	return 0;
+end:
+	Free(path);
+
+	return ret;
 }
 
 #define BUFF_LENGTH 64
@@ -65,27 +79,37 @@ ndctl_match_fsdax(dev_t st_dev, const char *devname)
 {
 	LOG(3, "st_dev %lu devname %s", st_dev, devname);
 
+	int ret = 0;
+	char *path;
+	char dev_id[BUFF_LENGTH];
+
 	if (*devname == '\0')
 		return 1;
 
-	char path[PATH_MAX];
-	char dev_id[BUFF_LENGTH];
+	path = Malloc(PATH_MAX * sizeof(char));
+	if (path == NULL) {
+		ERR("!Malloc");
+		return PMEM2_E_ERRNO;
+	}
 
 	if (util_snprintf(path, PATH_MAX, "/sys/block/%s/dev", devname) < 0) {
 		ERR("!snprintf");
-		return PMEM2_E_ERRNO;
+		ret = PMEM2_E_ERRNO;
+		goto end;
 	}
 
 	if (util_snprintf(dev_id, BUFF_LENGTH, "%d:%d",
 			major(st_dev), minor(st_dev)) < 0) {
 		ERR("!snprintf");
-		return PMEM2_E_ERRNO;
+		ret = PMEM2_E_ERRNO;
+		goto end;
 	}
 
 	int fd = os_open(path, O_RDONLY);
 	if (fd < 0) {
 		ERR("!open \"%s\"", path);
-		return PMEM2_E_ERRNO;
+		ret = PMEM2_E_ERRNO;
+		goto end;
 	}
 
 	char buff[BUFF_LENGTH];
@@ -95,31 +119,38 @@ ndctl_match_fsdax(dev_t st_dev, const char *devname)
 		int oerrno = errno; /* save the errno */
 		os_close(fd);
 		errno = oerrno;
-		return PMEM2_E_ERRNO;
+		ret = PMEM2_E_ERRNO;
+		goto end;
 	}
 
 	os_close(fd);
 
 	if (nread == 0) {
 		ERR("%s is empty", path);
-		return PMEM2_E_INVALID_DEV_FORMAT;
+		ret = PMEM2_E_INVALID_DEV_FORMAT;
+		goto end;
 	}
 
 	if (buff[nread - 1] != '\n') {
 		ERR("%s doesn't end with new line", path);
-		return PMEM2_E_INVALID_DEV_FORMAT;
+		ret = PMEM2_E_INVALID_DEV_FORMAT;
+		goto end;
 	}
 
 	buff[nread - 1] = '\0';
 
 	if (strcmp(buff, dev_id) != 0) {
 		LOG(10, "skipping not matching device: %s", path);
-		return 1;
+		ret = 1;
+		goto end;
 	}
 
 	LOG(4, "found matching device: %s", path);
 
-	return 0;
+end:
+	Free(path);
+
+	return ret;
 }
 
 /*