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v5.4
  1// SPDX-License-Identifier: GPL-2.0
  2#include "util.h"
  3#include "debug.h"
  4#include "event.h"
  5#include <api/fs/fs.h>
  6#include <sys/stat.h>
  7#include <sys/utsname.h>
  8#include <dirent.h>
  9#include <fcntl.h>
 10#include <inttypes.h>
 11#include <signal.h>
 12#include <stdio.h>
 13#include <stdlib.h>
 14#include <string.h>
 15#include <errno.h>
 16#include <limits.h>
 17#include <linux/capability.h>
 18#include <linux/kernel.h>
 19#include <linux/log2.h>
 20#include <linux/time64.h>
 
 21#include <unistd.h>
 22#include "cap.h"
 23#include "strlist.h"
 24#include "string2.h"
 25
 26/*
 27 * XXX We need to find a better place for these things...
 28 */
 29
 30bool perf_singlethreaded = true;
 31
 32void perf_set_singlethreaded(void)
 33{
 34	perf_singlethreaded = true;
 35}
 36
 37void perf_set_multithreaded(void)
 38{
 39	perf_singlethreaded = false;
 40}
 41
 42int sysctl_perf_event_max_stack = PERF_MAX_STACK_DEPTH;
 43int sysctl_perf_event_max_contexts_per_stack = PERF_MAX_CONTEXTS_PER_STACK;
 44
 45int sysctl__max_stack(void)
 46{
 47	int value;
 48
 49	if (sysctl__read_int("kernel/perf_event_max_stack", &value) == 0)
 50		sysctl_perf_event_max_stack = value;
 51
 52	if (sysctl__read_int("kernel/perf_event_max_contexts_per_stack", &value) == 0)
 53		sysctl_perf_event_max_contexts_per_stack = value;
 54
 55	return sysctl_perf_event_max_stack;
 56}
 57
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 58bool test_attr__enabled;
 59
 60bool perf_host  = true;
 61bool perf_guest = false;
 62
 63void event_attr_init(struct perf_event_attr *attr)
 64{
 65	if (!perf_host)
 66		attr->exclude_host  = 1;
 67	if (!perf_guest)
 68		attr->exclude_guest = 1;
 69	/* to capture ABI version */
 70	attr->size = sizeof(*attr);
 71}
 72
 73int mkdir_p(char *path, mode_t mode)
 74{
 75	struct stat st;
 76	int err;
 77	char *d = path;
 78
 79	if (*d != '/')
 80		return -1;
 81
 82	if (stat(path, &st) == 0)
 83		return 0;
 84
 85	while (*++d == '/');
 86
 87	while ((d = strchr(d, '/'))) {
 88		*d = '\0';
 89		err = stat(path, &st) && mkdir(path, mode);
 90		*d++ = '/';
 91		if (err)
 92			return -1;
 93		while (*d == '/')
 94			++d;
 95	}
 96	return (stat(path, &st) && mkdir(path, mode)) ? -1 : 0;
 97}
 98
 99static bool match_pat(char *file, const char **pat)
100{
101	int i = 0;
102
103	if (!pat)
104		return true;
105
106	while (pat[i]) {
107		if (strglobmatch(file, pat[i]))
108			return true;
109
110		i++;
111	}
112
113	return false;
114}
115
116/*
117 * The depth specify how deep the removal will go.
118 * 0       - will remove only files under the 'path' directory
119 * 1 .. x  - will dive in x-level deep under the 'path' directory
120 *
121 * If specified the pat is array of string patterns ended with NULL,
122 * which are checked upon every file/directory found. Only matching
123 * ones are removed.
124 *
125 * The function returns:
126 *    0 on success
127 *   -1 on removal failure with errno set
128 *   -2 on pattern failure
129 */
130static int rm_rf_depth_pat(const char *path, int depth, const char **pat)
131{
132	DIR *dir;
133	int ret;
134	struct dirent *d;
135	char namebuf[PATH_MAX];
136	struct stat statbuf;
137
138	/* Do not fail if there's no file. */
139	ret = lstat(path, &statbuf);
140	if (ret)
141		return 0;
142
143	/* Try to remove any file we get. */
144	if (!(statbuf.st_mode & S_IFDIR))
145		return unlink(path);
146
147	/* We have directory in path. */
148	dir = opendir(path);
149	if (dir == NULL)
150		return -1;
151
152	while ((d = readdir(dir)) != NULL && !ret) {
153
154		if (!strcmp(d->d_name, ".") || !strcmp(d->d_name, ".."))
155			continue;
156
157		if (!match_pat(d->d_name, pat)) {
158			ret =  -2;
159			break;
160		}
161
162		scnprintf(namebuf, sizeof(namebuf), "%s/%s",
163			  path, d->d_name);
164
165		/* We have to check symbolic link itself */
166		ret = lstat(namebuf, &statbuf);
167		if (ret < 0) {
168			pr_debug("stat failed: %s\n", namebuf);
169			break;
170		}
171
172		if (S_ISDIR(statbuf.st_mode))
173			ret = depth ? rm_rf_depth_pat(namebuf, depth - 1, pat) : 0;
174		else
175			ret = unlink(namebuf);
176	}
177	closedir(dir);
178
179	if (ret < 0)
180		return ret;
181
182	return rmdir(path);
183}
184
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
185int rm_rf_perf_data(const char *path)
186{
187	const char *pat[] = {
188		"header",
189		"data.*",
190		NULL,
191	};
192
 
 
193	return rm_rf_depth_pat(path, 0, pat);
194}
195
196int rm_rf(const char *path)
197{
198	return rm_rf_depth_pat(path, INT_MAX, NULL);
199}
200
201/* A filter which removes dot files */
202bool lsdir_no_dot_filter(const char *name __maybe_unused, struct dirent *d)
203{
204	return d->d_name[0] != '.';
205}
206
207/* lsdir reads a directory and store it in strlist */
208struct strlist *lsdir(const char *name,
209		      bool (*filter)(const char *, struct dirent *))
210{
211	struct strlist *list = NULL;
212	DIR *dir;
213	struct dirent *d;
214
215	dir = opendir(name);
216	if (!dir)
217		return NULL;
218
219	list = strlist__new(NULL, NULL);
220	if (!list) {
221		errno = ENOMEM;
222		goto out;
223	}
224
225	while ((d = readdir(dir)) != NULL) {
226		if (!filter || filter(name, d))
227			strlist__add(list, d->d_name);
228	}
229
230out:
231	closedir(dir);
232	return list;
233}
234
235size_t hex_width(u64 v)
236{
237	size_t n = 1;
238
239	while ((v >>= 4))
240		++n;
241
242	return n;
243}
244
245int perf_event_paranoid(void)
246{
247	int value;
248
249	if (sysctl__read_int("kernel/perf_event_paranoid", &value))
250		return INT_MAX;
251
252	return value;
253}
254
255bool perf_event_paranoid_check(int max_level)
256{
257	return perf_cap__capable(CAP_SYS_ADMIN) ||
 
258			perf_event_paranoid() <= max_level;
259}
260
261static int
262fetch_ubuntu_kernel_version(unsigned int *puint)
263{
264	ssize_t len;
265	size_t line_len = 0;
266	char *ptr, *line = NULL;
267	int version, patchlevel, sublevel, err;
268	FILE *vsig;
269
270	if (!puint)
271		return 0;
272
273	vsig = fopen("/proc/version_signature", "r");
274	if (!vsig) {
275		pr_debug("Open /proc/version_signature failed: %s\n",
276			 strerror(errno));
277		return -1;
278	}
279
280	len = getline(&line, &line_len, vsig);
281	fclose(vsig);
282	err = -1;
283	if (len <= 0) {
284		pr_debug("Reading from /proc/version_signature failed: %s\n",
285			 strerror(errno));
286		goto errout;
287	}
288
289	ptr = strrchr(line, ' ');
290	if (!ptr) {
291		pr_debug("Parsing /proc/version_signature failed: %s\n", line);
292		goto errout;
293	}
294
295	err = sscanf(ptr + 1, "%d.%d.%d",
296		     &version, &patchlevel, &sublevel);
297	if (err != 3) {
298		pr_debug("Unable to get kernel version from /proc/version_signature '%s'\n",
299			 line);
300		goto errout;
301	}
302
303	*puint = (version << 16) + (patchlevel << 8) + sublevel;
304	err = 0;
305errout:
306	free(line);
307	return err;
308}
309
310int
311fetch_kernel_version(unsigned int *puint, char *str,
312		     size_t str_size)
313{
314	struct utsname utsname;
315	int version, patchlevel, sublevel, err;
316	bool int_ver_ready = false;
317
318	if (access("/proc/version_signature", R_OK) == 0)
319		if (!fetch_ubuntu_kernel_version(puint))
320			int_ver_ready = true;
321
322	if (uname(&utsname))
323		return -1;
324
325	if (str && str_size) {
326		strncpy(str, utsname.release, str_size);
327		str[str_size - 1] = '\0';
328	}
329
330	if (!puint || int_ver_ready)
331		return 0;
332
333	err = sscanf(utsname.release, "%d.%d.%d",
334		     &version, &patchlevel, &sublevel);
335
336	if (err != 3) {
337		pr_debug("Unable to get kernel version from uname '%s'\n",
338			 utsname.release);
339		return -1;
340	}
341
342	*puint = (version << 16) + (patchlevel << 8) + sublevel;
343	return 0;
344}
345
346const char *perf_tip(const char *dirpath)
347{
348	struct strlist *tips;
349	struct str_node *node;
350	char *tip = NULL;
351	struct strlist_config conf = {
352		.dirname = dirpath,
353		.file_only = true,
354	};
 
355
 
356	tips = strlist__new("tips.txt", &conf);
357	if (tips == NULL)
358		return errno == ENOENT ? NULL :
359			"Tip: check path of tips.txt or get more memory! ;-p";
360
361	if (strlist__nr_entries(tips) == 0)
362		goto out;
363
364	node = strlist__entry(tips, random() % strlist__nr_entries(tips));
365	if (asprintf(&tip, "Tip: %s", node->s) < 0)
366		tip = (char *)"Tip: get more memory! ;-)";
367
368out:
369	strlist__delete(tips);
370
371	return tip;
372}
373
374char *perf_exe(char *buf, int len)
375{
376	int n = readlink("/proc/self/exe", buf, len);
377	if (n > 0) {
378		buf[n] = 0;
379		return buf;
380	}
381	return strcpy(buf, "perf");
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
382}
v6.2
  1// SPDX-License-Identifier: GPL-2.0
  2#include "util.h"
  3#include "debug.h"
  4#include "event.h"
  5#include <api/fs/fs.h>
  6#include <sys/stat.h>
  7#include <sys/utsname.h>
  8#include <dirent.h>
  9#include <fcntl.h>
 10#include <inttypes.h>
 11#include <signal.h>
 12#include <stdio.h>
 13#include <stdlib.h>
 14#include <string.h>
 15#include <errno.h>
 16#include <limits.h>
 17#include <linux/capability.h>
 18#include <linux/kernel.h>
 19#include <linux/log2.h>
 20#include <linux/time64.h>
 21#include <linux/overflow.h>
 22#include <unistd.h>
 23#include "cap.h"
 24#include "strlist.h"
 25#include "string2.h"
 26
 27/*
 28 * XXX We need to find a better place for these things...
 29 */
 30
 31bool perf_singlethreaded = true;
 32
 33void perf_set_singlethreaded(void)
 34{
 35	perf_singlethreaded = true;
 36}
 37
 38void perf_set_multithreaded(void)
 39{
 40	perf_singlethreaded = false;
 41}
 42
 43int sysctl_perf_event_max_stack = PERF_MAX_STACK_DEPTH;
 44int sysctl_perf_event_max_contexts_per_stack = PERF_MAX_CONTEXTS_PER_STACK;
 45
 46int sysctl__max_stack(void)
 47{
 48	int value;
 49
 50	if (sysctl__read_int("kernel/perf_event_max_stack", &value) == 0)
 51		sysctl_perf_event_max_stack = value;
 52
 53	if (sysctl__read_int("kernel/perf_event_max_contexts_per_stack", &value) == 0)
 54		sysctl_perf_event_max_contexts_per_stack = value;
 55
 56	return sysctl_perf_event_max_stack;
 57}
 58
 59bool sysctl__nmi_watchdog_enabled(void)
 60{
 61	static bool cached;
 62	static bool nmi_watchdog;
 63	int value;
 64
 65	if (cached)
 66		return nmi_watchdog;
 67
 68	if (sysctl__read_int("kernel/nmi_watchdog", &value) < 0)
 69		return false;
 70
 71	nmi_watchdog = (value > 0) ? true : false;
 72	cached = true;
 73
 74	return nmi_watchdog;
 75}
 76
 77bool test_attr__enabled;
 78
 79bool perf_host  = true;
 80bool perf_guest = false;
 81
 82void event_attr_init(struct perf_event_attr *attr)
 83{
 84	if (!perf_host)
 85		attr->exclude_host  = 1;
 86	if (!perf_guest)
 87		attr->exclude_guest = 1;
 88	/* to capture ABI version */
 89	attr->size = sizeof(*attr);
 90}
 91
 92int mkdir_p(char *path, mode_t mode)
 93{
 94	struct stat st;
 95	int err;
 96	char *d = path;
 97
 98	if (*d != '/')
 99		return -1;
100
101	if (stat(path, &st) == 0)
102		return 0;
103
104	while (*++d == '/');
105
106	while ((d = strchr(d, '/'))) {
107		*d = '\0';
108		err = stat(path, &st) && mkdir(path, mode);
109		*d++ = '/';
110		if (err)
111			return -1;
112		while (*d == '/')
113			++d;
114	}
115	return (stat(path, &st) && mkdir(path, mode)) ? -1 : 0;
116}
117
118static bool match_pat(char *file, const char **pat)
119{
120	int i = 0;
121
122	if (!pat)
123		return true;
124
125	while (pat[i]) {
126		if (strglobmatch(file, pat[i]))
127			return true;
128
129		i++;
130	}
131
132	return false;
133}
134
135/*
136 * The depth specify how deep the removal will go.
137 * 0       - will remove only files under the 'path' directory
138 * 1 .. x  - will dive in x-level deep under the 'path' directory
139 *
140 * If specified the pat is array of string patterns ended with NULL,
141 * which are checked upon every file/directory found. Only matching
142 * ones are removed.
143 *
144 * The function returns:
145 *    0 on success
146 *   -1 on removal failure with errno set
147 *   -2 on pattern failure
148 */
149static int rm_rf_depth_pat(const char *path, int depth, const char **pat)
150{
151	DIR *dir;
152	int ret;
153	struct dirent *d;
154	char namebuf[PATH_MAX];
155	struct stat statbuf;
156
157	/* Do not fail if there's no file. */
158	ret = lstat(path, &statbuf);
159	if (ret)
160		return 0;
161
162	/* Try to remove any file we get. */
163	if (!(statbuf.st_mode & S_IFDIR))
164		return unlink(path);
165
166	/* We have directory in path. */
167	dir = opendir(path);
168	if (dir == NULL)
169		return -1;
170
171	while ((d = readdir(dir)) != NULL && !ret) {
172
173		if (!strcmp(d->d_name, ".") || !strcmp(d->d_name, ".."))
174			continue;
175
176		if (!match_pat(d->d_name, pat)) {
177			ret =  -2;
178			break;
179		}
180
181		scnprintf(namebuf, sizeof(namebuf), "%s/%s",
182			  path, d->d_name);
183
184		/* We have to check symbolic link itself */
185		ret = lstat(namebuf, &statbuf);
186		if (ret < 0) {
187			pr_debug("stat failed: %s\n", namebuf);
188			break;
189		}
190
191		if (S_ISDIR(statbuf.st_mode))
192			ret = depth ? rm_rf_depth_pat(namebuf, depth - 1, pat) : 0;
193		else
194			ret = unlink(namebuf);
195	}
196	closedir(dir);
197
198	if (ret < 0)
199		return ret;
200
201	return rmdir(path);
202}
203
204static int rm_rf_a_kcore_dir(const char *path, const char *name)
205{
206	char kcore_dir_path[PATH_MAX];
207	const char *pat[] = {
208		"kcore",
209		"kallsyms",
210		"modules",
211		NULL,
212	};
213
214	snprintf(kcore_dir_path, sizeof(kcore_dir_path), "%s/%s", path, name);
215
216	return rm_rf_depth_pat(kcore_dir_path, 0, pat);
217}
218
219static bool kcore_dir_filter(const char *name __maybe_unused, struct dirent *d)
220{
221	const char *pat[] = {
222		"kcore_dir",
223		"kcore_dir__[1-9]*",
224		NULL,
225	};
226
227	return match_pat(d->d_name, pat);
228}
229
230static int rm_rf_kcore_dir(const char *path)
231{
232	struct strlist *kcore_dirs;
233	struct str_node *nd;
234	int ret;
235
236	kcore_dirs = lsdir(path, kcore_dir_filter);
237
238	if (!kcore_dirs)
239		return 0;
240
241	strlist__for_each_entry(nd, kcore_dirs) {
242		ret = rm_rf_a_kcore_dir(path, nd->s);
243		if (ret)
244			return ret;
245	}
246
247	strlist__delete(kcore_dirs);
248
249	return 0;
250}
251
252int rm_rf_perf_data(const char *path)
253{
254	const char *pat[] = {
255		"data",
256		"data.*",
257		NULL,
258	};
259
260	rm_rf_kcore_dir(path);
261
262	return rm_rf_depth_pat(path, 0, pat);
263}
264
265int rm_rf(const char *path)
266{
267	return rm_rf_depth_pat(path, INT_MAX, NULL);
268}
269
270/* A filter which removes dot files */
271bool lsdir_no_dot_filter(const char *name __maybe_unused, struct dirent *d)
272{
273	return d->d_name[0] != '.';
274}
275
276/* lsdir reads a directory and store it in strlist */
277struct strlist *lsdir(const char *name,
278		      bool (*filter)(const char *, struct dirent *))
279{
280	struct strlist *list = NULL;
281	DIR *dir;
282	struct dirent *d;
283
284	dir = opendir(name);
285	if (!dir)
286		return NULL;
287
288	list = strlist__new(NULL, NULL);
289	if (!list) {
290		errno = ENOMEM;
291		goto out;
292	}
293
294	while ((d = readdir(dir)) != NULL) {
295		if (!filter || filter(name, d))
296			strlist__add(list, d->d_name);
297	}
298
299out:
300	closedir(dir);
301	return list;
302}
303
304size_t hex_width(u64 v)
305{
306	size_t n = 1;
307
308	while ((v >>= 4))
309		++n;
310
311	return n;
312}
313
314int perf_event_paranoid(void)
315{
316	int value;
317
318	if (sysctl__read_int("kernel/perf_event_paranoid", &value))
319		return INT_MAX;
320
321	return value;
322}
323
324bool perf_event_paranoid_check(int max_level)
325{
326	return perf_cap__capable(CAP_SYS_ADMIN) ||
327			perf_cap__capable(CAP_PERFMON) ||
328			perf_event_paranoid() <= max_level;
329}
330
331static int
332fetch_ubuntu_kernel_version(unsigned int *puint)
333{
334	ssize_t len;
335	size_t line_len = 0;
336	char *ptr, *line = NULL;
337	int version, patchlevel, sublevel, err;
338	FILE *vsig;
339
340	if (!puint)
341		return 0;
342
343	vsig = fopen("/proc/version_signature", "r");
344	if (!vsig) {
345		pr_debug("Open /proc/version_signature failed: %s\n",
346			 strerror(errno));
347		return -1;
348	}
349
350	len = getline(&line, &line_len, vsig);
351	fclose(vsig);
352	err = -1;
353	if (len <= 0) {
354		pr_debug("Reading from /proc/version_signature failed: %s\n",
355			 strerror(errno));
356		goto errout;
357	}
358
359	ptr = strrchr(line, ' ');
360	if (!ptr) {
361		pr_debug("Parsing /proc/version_signature failed: %s\n", line);
362		goto errout;
363	}
364
365	err = sscanf(ptr + 1, "%d.%d.%d",
366		     &version, &patchlevel, &sublevel);
367	if (err != 3) {
368		pr_debug("Unable to get kernel version from /proc/version_signature '%s'\n",
369			 line);
370		goto errout;
371	}
372
373	*puint = (version << 16) + (patchlevel << 8) + sublevel;
374	err = 0;
375errout:
376	free(line);
377	return err;
378}
379
380int
381fetch_kernel_version(unsigned int *puint, char *str,
382		     size_t str_size)
383{
384	struct utsname utsname;
385	int version, patchlevel, sublevel, err;
386	bool int_ver_ready = false;
387
388	if (access("/proc/version_signature", R_OK) == 0)
389		if (!fetch_ubuntu_kernel_version(puint))
390			int_ver_ready = true;
391
392	if (uname(&utsname))
393		return -1;
394
395	if (str && str_size) {
396		strncpy(str, utsname.release, str_size);
397		str[str_size - 1] = '\0';
398	}
399
400	if (!puint || int_ver_ready)
401		return 0;
402
403	err = sscanf(utsname.release, "%d.%d.%d",
404		     &version, &patchlevel, &sublevel);
405
406	if (err != 3) {
407		pr_debug("Unable to get kernel version from uname '%s'\n",
408			 utsname.release);
409		return -1;
410	}
411
412	*puint = (version << 16) + (patchlevel << 8) + sublevel;
413	return 0;
414}
415
416int perf_tip(char **strp, const char *dirpath)
417{
418	struct strlist *tips;
419	struct str_node *node;
 
420	struct strlist_config conf = {
421		.dirname = dirpath,
422		.file_only = true,
423	};
424	int ret = 0;
425
426	*strp = NULL;
427	tips = strlist__new("tips.txt", &conf);
428	if (tips == NULL)
429		return -errno;
 
430
431	if (strlist__nr_entries(tips) == 0)
432		goto out;
433
434	node = strlist__entry(tips, random() % strlist__nr_entries(tips));
435	if (asprintf(strp, "Tip: %s", node->s) < 0)
436		ret = -ENOMEM;
437
438out:
439	strlist__delete(tips);
440
441	return ret;
442}
443
444char *perf_exe(char *buf, int len)
445{
446	int n = readlink("/proc/self/exe", buf, len);
447	if (n > 0) {
448		buf[n] = 0;
449		return buf;
450	}
451	return strcpy(buf, "perf");
452}
453
454void perf_debuginfod_setup(struct perf_debuginfod *di)
455{
456	/*
457	 * By default '!di->set' we clear DEBUGINFOD_URLS, so debuginfod
458	 * processing is not triggered, otherwise we set it to 'di->urls'
459	 * value. If 'di->urls' is "system" we keep DEBUGINFOD_URLS value.
460	 */
461	if (!di->set)
462		setenv("DEBUGINFOD_URLS", "", 1);
463	else if (di->urls && strcmp(di->urls, "system"))
464		setenv("DEBUGINFOD_URLS", di->urls, 1);
465
466	pr_debug("DEBUGINFOD_URLS=%s\n", getenv("DEBUGINFOD_URLS"));
467
468#ifndef HAVE_DEBUGINFOD_SUPPORT
469	if (di->set)
470		pr_warning("WARNING: debuginfod support requested, but perf is not built with it\n");
471#endif
472}
473
474/*
475 * Return a new filename prepended with task's root directory if it's in
476 * a chroot.  Callers should free the returned string.
477 */
478char *filename_with_chroot(int pid, const char *filename)
479{
480	char buf[PATH_MAX];
481	char proc_root[32];
482	char *new_name = NULL;
483	int ret;
484
485	scnprintf(proc_root, sizeof(proc_root), "/proc/%d/root", pid);
486	ret = readlink(proc_root, buf, sizeof(buf) - 1);
487	if (ret <= 0)
488		return NULL;
489
490	/* readlink(2) does not append a null byte to buf */
491	buf[ret] = '\0';
492
493	if (!strcmp(buf, "/"))
494		return NULL;
495
496	if (strstr(buf, "(deleted)"))
497		return NULL;
498
499	if (asprintf(&new_name, "%s/%s", buf, filename) < 0)
500		return NULL;
501
502	return new_name;
503}
504
505/*
506 * Reallocate an array *arr of size *arr_sz so that it is big enough to contain
507 * x elements of size msz, initializing new entries to *init_val or zero if
508 * init_val is NULL
509 */
510int do_realloc_array_as_needed(void **arr, size_t *arr_sz, size_t x, size_t msz, const void *init_val)
511{
512	size_t new_sz = *arr_sz;
513	void *new_arr;
514	size_t i;
515
516	if (!new_sz)
517		new_sz = msz >= 64 ? 1 : roundup(64, msz); /* Start with at least 64 bytes */
518	while (x >= new_sz) {
519		if (check_mul_overflow(new_sz, (size_t)2, &new_sz))
520			return -ENOMEM;
521	}
522	if (new_sz == *arr_sz)
523		return 0;
524	new_arr = calloc(new_sz, msz);
525	if (!new_arr)
526		return -ENOMEM;
527	memcpy(new_arr, *arr, *arr_sz * msz);
528	if (init_val) {
529		for (i = *arr_sz; i < new_sz; i++)
530			memcpy(new_arr + (i * msz), init_val, msz);
531	}
532	*arr = new_arr;
533	*arr_sz = new_sz;
534	return 0;
535}