iwlwifi: replace d0i3_mode and wowlan_d0i3 with more generic variables
[linux/fpc-iii.git] / tools / iio / iio_utils.c
blob5eb6793f3972e64ed2c46533cd2e6aa5d65168fa
1 /* IIO - useful set of util functionality
3 * Copyright (c) 2008 Jonathan Cameron
5 * This program is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 as published by
7 * the Free Software Foundation.
8 */
9 #include <string.h>
10 #include <stdlib.h>
11 #include <stdio.h>
12 #include <stdint.h>
13 #include <dirent.h>
14 #include <errno.h>
15 #include <ctype.h>
16 #include "iio_utils.h"
18 const char *iio_dir = "/sys/bus/iio/devices/";
20 static char * const iio_direction[] = {
21 "in",
22 "out",
25 /**
26 * iioutils_break_up_name() - extract generic name from full channel name
27 * @full_name: the full channel name
28 * @generic_name: the output generic channel name
30 * Returns 0 on success, or a negative error code if string extraction failed.
31 **/
32 int iioutils_break_up_name(const char *full_name, char **generic_name)
34 char *current;
35 char *w, *r;
36 char *working, *prefix = "";
37 int i, ret;
39 for (i = 0; i < ARRAY_SIZE(iio_direction); i++)
40 if (!strncmp(full_name, iio_direction[i],
41 strlen(iio_direction[i]))) {
42 prefix = iio_direction[i];
43 break;
46 current = strdup(full_name + strlen(prefix) + 1);
47 if (!current)
48 return -ENOMEM;
50 working = strtok(current, "_\0");
51 if (!working) {
52 free(current);
53 return -EINVAL;
56 w = working;
57 r = working;
59 while (*r != '\0') {
60 if (!isdigit(*r)) {
61 *w = *r;
62 w++;
65 r++;
67 *w = '\0';
68 ret = asprintf(generic_name, "%s_%s", prefix, working);
69 free(current);
71 return (ret == -1) ? -ENOMEM : 0;
74 /**
75 * iioutils_get_type() - find and process _type attribute data
76 * @is_signed: output whether channel is signed
77 * @bytes: output how many bytes the channel storage occupies
78 * @bits_used: output number of valid bits of data
79 * @shift: output amount of bits to shift right data before applying bit mask
80 * @mask: output a bit mask for the raw data
81 * @be: output if data in big endian
82 * @device_dir: the IIO device directory
83 * @name: the channel name
84 * @generic_name: the channel type name
86 * Returns a value >= 0 on success, otherwise a negative error code.
87 **/
88 int iioutils_get_type(unsigned *is_signed, unsigned *bytes, unsigned *bits_used,
89 unsigned *shift, uint64_t *mask, unsigned *be,
90 const char *device_dir, const char *name,
91 const char *generic_name)
93 FILE *sysfsfp;
94 int ret;
95 DIR *dp;
96 char *scan_el_dir, *builtname, *builtname_generic, *filename = 0;
97 char signchar, endianchar;
98 unsigned padint;
99 const struct dirent *ent;
101 ret = asprintf(&scan_el_dir, FORMAT_SCAN_ELEMENTS_DIR, device_dir);
102 if (ret < 0)
103 return -ENOMEM;
105 ret = asprintf(&builtname, FORMAT_TYPE_FILE, name);
106 if (ret < 0) {
107 ret = -ENOMEM;
108 goto error_free_scan_el_dir;
110 ret = asprintf(&builtname_generic, FORMAT_TYPE_FILE, generic_name);
111 if (ret < 0) {
112 ret = -ENOMEM;
113 goto error_free_builtname;
116 dp = opendir(scan_el_dir);
117 if (!dp) {
118 ret = -errno;
119 goto error_free_builtname_generic;
122 ret = -ENOENT;
123 while (ent = readdir(dp), ent)
125 * Do we allow devices to override a generic name with
126 * a specific one?
128 if ((strcmp(builtname, ent->d_name) == 0) ||
129 (strcmp(builtname_generic, ent->d_name) == 0)) {
130 ret = asprintf(&filename,
131 "%s/%s", scan_el_dir, ent->d_name);
132 if (ret < 0) {
133 ret = -ENOMEM;
134 goto error_closedir;
137 sysfsfp = fopen(filename, "r");
138 if (!sysfsfp) {
139 ret = -errno;
140 fprintf(stderr, "failed to open %s\n",
141 filename);
142 goto error_free_filename;
145 ret = fscanf(sysfsfp,
146 "%ce:%c%u/%u>>%u",
147 &endianchar,
148 &signchar,
149 bits_used,
150 &padint, shift);
151 if (ret < 0) {
152 ret = -errno;
153 fprintf(stderr,
154 "failed to pass scan type description\n");
155 goto error_close_sysfsfp;
156 } else if (ret != 5) {
157 ret = -EIO;
158 fprintf(stderr,
159 "scan type description didn't match\n");
160 goto error_close_sysfsfp;
163 *be = (endianchar == 'b');
164 *bytes = padint / 8;
165 if (*bits_used == 64)
166 *mask = ~0;
167 else
168 *mask = (1ULL << *bits_used) - 1;
170 *is_signed = (signchar == 's');
171 if (fclose(sysfsfp)) {
172 ret = -errno;
173 fprintf(stderr, "Failed to close %s\n",
174 filename);
175 goto error_free_filename;
178 sysfsfp = 0;
179 free(filename);
180 filename = 0;
183 error_close_sysfsfp:
184 if (sysfsfp)
185 if (fclose(sysfsfp))
186 perror("iioutils_get_type(): Failed to close file");
188 error_free_filename:
189 if (filename)
190 free(filename);
192 error_closedir:
193 if (closedir(dp) == -1)
194 perror("iioutils_get_type(): Failed to close directory");
196 error_free_builtname_generic:
197 free(builtname_generic);
198 error_free_builtname:
199 free(builtname);
200 error_free_scan_el_dir:
201 free(scan_el_dir);
203 return ret;
207 * iioutils_get_param_float() - read a float value from a channel parameter
208 * @output: output the float value
209 * @param_name: the parameter name to read
210 * @device_dir: the IIO device directory in sysfs
211 * @name: the channel name
212 * @generic_name: the channel type name
214 * Returns a value >= 0 on success, otherwise a negative error code.
216 int iioutils_get_param_float(float *output, const char *param_name,
217 const char *device_dir, const char *name,
218 const char *generic_name)
220 FILE *sysfsfp;
221 int ret;
222 DIR *dp;
223 char *builtname, *builtname_generic;
224 char *filename = NULL;
225 const struct dirent *ent;
227 ret = asprintf(&builtname, "%s_%s", name, param_name);
228 if (ret < 0)
229 return -ENOMEM;
231 ret = asprintf(&builtname_generic,
232 "%s_%s", generic_name, param_name);
233 if (ret < 0) {
234 ret = -ENOMEM;
235 goto error_free_builtname;
238 dp = opendir(device_dir);
239 if (!dp) {
240 ret = -errno;
241 goto error_free_builtname_generic;
244 ret = -ENOENT;
245 while (ent = readdir(dp), ent)
246 if ((strcmp(builtname, ent->d_name) == 0) ||
247 (strcmp(builtname_generic, ent->d_name) == 0)) {
248 ret = asprintf(&filename,
249 "%s/%s", device_dir, ent->d_name);
250 if (ret < 0) {
251 ret = -ENOMEM;
252 goto error_closedir;
255 sysfsfp = fopen(filename, "r");
256 if (!sysfsfp) {
257 ret = -errno;
258 goto error_free_filename;
261 errno = 0;
262 if (fscanf(sysfsfp, "%f", output) != 1)
263 ret = errno ? -errno : -ENODATA;
265 break;
267 error_free_filename:
268 if (filename)
269 free(filename);
271 error_closedir:
272 if (closedir(dp) == -1)
273 perror("iioutils_get_param_float(): Failed to close directory");
275 error_free_builtname_generic:
276 free(builtname_generic);
277 error_free_builtname:
278 free(builtname);
280 return ret;
284 * bsort_channel_array_by_index() - sort the array in index order
285 * @ci_array: the iio_channel_info array to be sorted
286 * @cnt: the amount of array elements
289 void bsort_channel_array_by_index(struct iio_channel_info *ci_array, int cnt)
291 struct iio_channel_info temp;
292 int x, y;
294 for (x = 0; x < cnt; x++)
295 for (y = 0; y < (cnt - 1); y++)
296 if (ci_array[y].index > ci_array[y + 1].index) {
297 temp = ci_array[y + 1];
298 ci_array[y + 1] = ci_array[y];
299 ci_array[y] = temp;
304 * build_channel_array() - function to figure out what channels are present
305 * @device_dir: the IIO device directory in sysfs
306 * @ci_array: output the resulting array of iio_channel_info
307 * @counter: output the amount of array elements
309 * Returns 0 on success, otherwise a negative error code.
311 int build_channel_array(const char *device_dir,
312 struct iio_channel_info **ci_array, int *counter)
314 DIR *dp;
315 FILE *sysfsfp;
316 int count = 0, i;
317 struct iio_channel_info *current;
318 int ret;
319 const struct dirent *ent;
320 char *scan_el_dir;
321 char *filename;
323 *counter = 0;
324 ret = asprintf(&scan_el_dir, FORMAT_SCAN_ELEMENTS_DIR, device_dir);
325 if (ret < 0)
326 return -ENOMEM;
328 dp = opendir(scan_el_dir);
329 if (!dp) {
330 ret = -errno;
331 goto error_free_name;
334 while (ent = readdir(dp), ent)
335 if (strcmp(ent->d_name + strlen(ent->d_name) - strlen("_en"),
336 "_en") == 0) {
337 ret = asprintf(&filename,
338 "%s/%s", scan_el_dir, ent->d_name);
339 if (ret < 0) {
340 ret = -ENOMEM;
341 goto error_close_dir;
344 sysfsfp = fopen(filename, "r");
345 if (!sysfsfp) {
346 ret = -errno;
347 free(filename);
348 goto error_close_dir;
351 errno = 0;
352 if (fscanf(sysfsfp, "%i", &ret) != 1) {
353 ret = errno ? -errno : -ENODATA;
354 if (fclose(sysfsfp))
355 perror("build_channel_array(): Failed to close file");
357 free(filename);
358 goto error_close_dir;
360 if (ret == 1)
361 (*counter)++;
363 if (fclose(sysfsfp)) {
364 ret = -errno;
365 free(filename);
366 goto error_close_dir;
369 free(filename);
372 *ci_array = malloc(sizeof(**ci_array) * (*counter));
373 if (!*ci_array) {
374 ret = -ENOMEM;
375 goto error_close_dir;
378 seekdir(dp, 0);
379 while (ent = readdir(dp), ent) {
380 if (strcmp(ent->d_name + strlen(ent->d_name) - strlen("_en"),
381 "_en") == 0) {
382 int current_enabled = 0;
384 current = &(*ci_array)[count++];
385 ret = asprintf(&filename,
386 "%s/%s", scan_el_dir, ent->d_name);
387 if (ret < 0) {
388 ret = -ENOMEM;
389 /* decrement count to avoid freeing name */
390 count--;
391 goto error_cleanup_array;
394 sysfsfp = fopen(filename, "r");
395 if (!sysfsfp) {
396 ret = -errno;
397 free(filename);
398 count--;
399 goto error_cleanup_array;
402 errno = 0;
403 if (fscanf(sysfsfp, "%i", &current_enabled) != 1) {
404 ret = errno ? -errno : -ENODATA;
405 free(filename);
406 count--;
407 goto error_cleanup_array;
410 if (fclose(sysfsfp)) {
411 ret = -errno;
412 free(filename);
413 count--;
414 goto error_cleanup_array;
417 if (!current_enabled) {
418 free(filename);
419 count--;
420 continue;
423 current->scale = 1.0;
424 current->offset = 0;
425 current->name = strndup(ent->d_name,
426 strlen(ent->d_name) -
427 strlen("_en"));
428 if (!current->name) {
429 free(filename);
430 ret = -ENOMEM;
431 count--;
432 goto error_cleanup_array;
435 /* Get the generic and specific name elements */
436 ret = iioutils_break_up_name(current->name,
437 &current->generic_name);
438 if (ret) {
439 free(filename);
440 free(current->name);
441 count--;
442 goto error_cleanup_array;
445 ret = asprintf(&filename,
446 "%s/%s_index",
447 scan_el_dir,
448 current->name);
449 if (ret < 0) {
450 free(filename);
451 ret = -ENOMEM;
452 goto error_cleanup_array;
455 sysfsfp = fopen(filename, "r");
456 if (!sysfsfp) {
457 ret = -errno;
458 fprintf(stderr, "failed to open %s\n",
459 filename);
460 free(filename);
461 goto error_cleanup_array;
464 errno = 0;
465 if (fscanf(sysfsfp, "%u", &current->index) != 1) {
466 ret = errno ? -errno : -ENODATA;
467 if (fclose(sysfsfp))
468 perror("build_channel_array(): Failed to close file");
470 free(filename);
471 goto error_cleanup_array;
474 if (fclose(sysfsfp)) {
475 ret = -errno;
476 free(filename);
477 goto error_cleanup_array;
480 free(filename);
481 /* Find the scale */
482 ret = iioutils_get_param_float(&current->scale,
483 "scale",
484 device_dir,
485 current->name,
486 current->generic_name);
487 if ((ret < 0) && (ret != -ENOENT))
488 goto error_cleanup_array;
490 ret = iioutils_get_param_float(&current->offset,
491 "offset",
492 device_dir,
493 current->name,
494 current->generic_name);
495 if ((ret < 0) && (ret != -ENOENT))
496 goto error_cleanup_array;
498 ret = iioutils_get_type(&current->is_signed,
499 &current->bytes,
500 &current->bits_used,
501 &current->shift,
502 &current->mask,
503 &current->be,
504 device_dir,
505 current->name,
506 current->generic_name);
507 if (ret < 0)
508 goto error_cleanup_array;
512 if (closedir(dp) == -1) {
513 ret = -errno;
514 goto error_cleanup_array;
517 free(scan_el_dir);
518 /* reorder so that the array is in index order */
519 bsort_channel_array_by_index(*ci_array, *counter);
521 return 0;
523 error_cleanup_array:
524 for (i = count - 1; i >= 0; i--) {
525 free((*ci_array)[i].name);
526 free((*ci_array)[i].generic_name);
528 free(*ci_array);
529 *ci_array = NULL;
530 *counter = 0;
531 error_close_dir:
532 if (dp)
533 if (closedir(dp) == -1)
534 perror("build_channel_array(): Failed to close dir");
536 error_free_name:
537 free(scan_el_dir);
539 return ret;
542 static int calc_digits(int num)
544 int count = 0;
546 while (num != 0) {
547 num /= 10;
548 count++;
551 return count;
555 * find_type_by_name() - function to match top level types by name
556 * @name: top level type instance name
557 * @type: the type of top level instance being searched
559 * Returns the device number of a matched IIO device on success, otherwise a
560 * negative error code.
561 * Typical types this is used for are device and trigger.
563 int find_type_by_name(const char *name, const char *type)
565 const struct dirent *ent;
566 int number, numstrlen, ret;
568 FILE *namefp;
569 DIR *dp;
570 char thisname[IIO_MAX_NAME_LENGTH];
571 char *filename;
573 dp = opendir(iio_dir);
574 if (!dp) {
575 fprintf(stderr, "No industrialio devices available\n");
576 return -ENODEV;
579 while (ent = readdir(dp), ent) {
580 if (strcmp(ent->d_name, ".") != 0 &&
581 strcmp(ent->d_name, "..") != 0 &&
582 strlen(ent->d_name) > strlen(type) &&
583 strncmp(ent->d_name, type, strlen(type)) == 0) {
584 errno = 0;
585 ret = sscanf(ent->d_name + strlen(type), "%d", &number);
586 if (ret < 0) {
587 ret = -errno;
588 fprintf(stderr,
589 "failed to read element number\n");
590 goto error_close_dir;
591 } else if (ret != 1) {
592 ret = -EIO;
593 fprintf(stderr,
594 "failed to match element number\n");
595 goto error_close_dir;
598 numstrlen = calc_digits(number);
599 /* verify the next character is not a colon */
600 if (strncmp(ent->d_name + strlen(type) + numstrlen,
601 ":", 1) != 0) {
602 filename = malloc(strlen(iio_dir) + strlen(type)
603 + numstrlen + 6);
604 if (!filename) {
605 ret = -ENOMEM;
606 goto error_close_dir;
609 ret = sprintf(filename, "%s%s%d/name", iio_dir,
610 type, number);
611 if (ret < 0) {
612 free(filename);
613 goto error_close_dir;
616 namefp = fopen(filename, "r");
617 if (!namefp) {
618 free(filename);
619 continue;
622 free(filename);
623 errno = 0;
624 if (fscanf(namefp, "%s", thisname) != 1) {
625 ret = errno ? -errno : -ENODATA;
626 goto error_close_dir;
629 if (fclose(namefp)) {
630 ret = -errno;
631 goto error_close_dir;
634 if (strcmp(name, thisname) == 0) {
635 if (closedir(dp) == -1)
636 return -errno;
638 return number;
643 if (closedir(dp) == -1)
644 return -errno;
646 return -ENODEV;
648 error_close_dir:
649 if (closedir(dp) == -1)
650 perror("find_type_by_name(): Failed to close directory");
652 return ret;
655 static int _write_sysfs_int(const char *filename, const char *basedir, int val,
656 int verify)
658 int ret = 0;
659 FILE *sysfsfp;
660 int test;
661 char *temp = malloc(strlen(basedir) + strlen(filename) + 2);
663 if (!temp)
664 return -ENOMEM;
666 ret = sprintf(temp, "%s/%s", basedir, filename);
667 if (ret < 0)
668 goto error_free;
670 sysfsfp = fopen(temp, "w");
671 if (!sysfsfp) {
672 ret = -errno;
673 fprintf(stderr, "failed to open %s\n", temp);
674 goto error_free;
677 ret = fprintf(sysfsfp, "%d", val);
678 if (ret < 0) {
679 if (fclose(sysfsfp))
680 perror("_write_sysfs_int(): Failed to close dir");
682 goto error_free;
685 if (fclose(sysfsfp)) {
686 ret = -errno;
687 goto error_free;
690 if (verify) {
691 sysfsfp = fopen(temp, "r");
692 if (!sysfsfp) {
693 ret = -errno;
694 fprintf(stderr, "failed to open %s\n", temp);
695 goto error_free;
698 if (fscanf(sysfsfp, "%d", &test) != 1) {
699 ret = errno ? -errno : -ENODATA;
700 if (fclose(sysfsfp))
701 perror("_write_sysfs_int(): Failed to close dir");
703 goto error_free;
706 if (fclose(sysfsfp)) {
707 ret = -errno;
708 goto error_free;
711 if (test != val) {
712 fprintf(stderr,
713 "Possible failure in int write %d to %s/%s\n",
714 val, basedir, filename);
715 ret = -1;
719 error_free:
720 free(temp);
721 return ret;
725 * write_sysfs_int() - write an integer value to a sysfs file
726 * @filename: name of the file to write to
727 * @basedir: the sysfs directory in which the file is to be found
728 * @val: integer value to write to file
730 * Returns a value >= 0 on success, otherwise a negative error code.
732 int write_sysfs_int(const char *filename, const char *basedir, int val)
734 return _write_sysfs_int(filename, basedir, val, 0);
738 * write_sysfs_int_and_verify() - write an integer value to a sysfs file
739 * and verify
740 * @filename: name of the file to write to
741 * @basedir: the sysfs directory in which the file is to be found
742 * @val: integer value to write to file
744 * Returns a value >= 0 on success, otherwise a negative error code.
746 int write_sysfs_int_and_verify(const char *filename, const char *basedir,
747 int val)
749 return _write_sysfs_int(filename, basedir, val, 1);
752 static int _write_sysfs_string(const char *filename, const char *basedir,
753 const char *val, int verify)
755 int ret = 0;
756 FILE *sysfsfp;
757 char *temp = malloc(strlen(basedir) + strlen(filename) + 2);
759 if (!temp) {
760 fprintf(stderr, "Memory allocation failed\n");
761 return -ENOMEM;
764 ret = sprintf(temp, "%s/%s", basedir, filename);
765 if (ret < 0)
766 goto error_free;
768 sysfsfp = fopen(temp, "w");
769 if (!sysfsfp) {
770 ret = -errno;
771 fprintf(stderr, "Could not open %s\n", temp);
772 goto error_free;
775 ret = fprintf(sysfsfp, "%s", val);
776 if (ret < 0) {
777 if (fclose(sysfsfp))
778 perror("_write_sysfs_string(): Failed to close dir");
780 goto error_free;
783 if (fclose(sysfsfp)) {
784 ret = -errno;
785 goto error_free;
788 if (verify) {
789 sysfsfp = fopen(temp, "r");
790 if (!sysfsfp) {
791 ret = -errno;
792 fprintf(stderr, "Could not open file to verify\n");
793 goto error_free;
796 if (fscanf(sysfsfp, "%s", temp) != 1) {
797 ret = errno ? -errno : -ENODATA;
798 if (fclose(sysfsfp))
799 perror("_write_sysfs_string(): Failed to close dir");
801 goto error_free;
804 if (fclose(sysfsfp)) {
805 ret = -errno;
806 goto error_free;
809 if (strcmp(temp, val) != 0) {
810 fprintf(stderr,
811 "Possible failure in string write of %s "
812 "Should be %s written to %s/%s\n", temp, val,
813 basedir, filename);
814 ret = -1;
818 error_free:
819 free(temp);
821 return ret;
825 * write_sysfs_string_and_verify() - string write, readback and verify
826 * @filename: name of file to write to
827 * @basedir: the sysfs directory in which the file is to be found
828 * @val: the string to write
830 * Returns a value >= 0 on success, otherwise a negative error code.
832 int write_sysfs_string_and_verify(const char *filename, const char *basedir,
833 const char *val)
835 return _write_sysfs_string(filename, basedir, val, 1);
839 * write_sysfs_string() - write string to a sysfs file
840 * @filename: name of file to write to
841 * @basedir: the sysfs directory in which the file is to be found
842 * @val: the string to write
844 * Returns a value >= 0 on success, otherwise a negative error code.
846 int write_sysfs_string(const char *filename, const char *basedir,
847 const char *val)
849 return _write_sysfs_string(filename, basedir, val, 0);
853 * read_sysfs_posint() - read an integer value from file
854 * @filename: name of file to read from
855 * @basedir: the sysfs directory in which the file is to be found
857 * Returns the read integer value >= 0 on success, otherwise a negative error
858 * code.
860 int read_sysfs_posint(const char *filename, const char *basedir)
862 int ret;
863 FILE *sysfsfp;
864 char *temp = malloc(strlen(basedir) + strlen(filename) + 2);
866 if (!temp) {
867 fprintf(stderr, "Memory allocation failed");
868 return -ENOMEM;
871 ret = sprintf(temp, "%s/%s", basedir, filename);
872 if (ret < 0)
873 goto error_free;
875 sysfsfp = fopen(temp, "r");
876 if (!sysfsfp) {
877 ret = -errno;
878 goto error_free;
881 errno = 0;
882 if (fscanf(sysfsfp, "%d\n", &ret) != 1) {
883 ret = errno ? -errno : -ENODATA;
884 if (fclose(sysfsfp))
885 perror("read_sysfs_posint(): Failed to close dir");
887 goto error_free;
890 if (fclose(sysfsfp))
891 ret = -errno;
893 error_free:
894 free(temp);
896 return ret;
900 * read_sysfs_float() - read a float value from file
901 * @filename: name of file to read from
902 * @basedir: the sysfs directory in which the file is to be found
903 * @val: output the read float value
905 * Returns a value >= 0 on success, otherwise a negative error code.
907 int read_sysfs_float(const char *filename, const char *basedir, float *val)
909 int ret = 0;
910 FILE *sysfsfp;
911 char *temp = malloc(strlen(basedir) + strlen(filename) + 2);
913 if (!temp) {
914 fprintf(stderr, "Memory allocation failed");
915 return -ENOMEM;
918 ret = sprintf(temp, "%s/%s", basedir, filename);
919 if (ret < 0)
920 goto error_free;
922 sysfsfp = fopen(temp, "r");
923 if (!sysfsfp) {
924 ret = -errno;
925 goto error_free;
928 errno = 0;
929 if (fscanf(sysfsfp, "%f\n", val) != 1) {
930 ret = errno ? -errno : -ENODATA;
931 if (fclose(sysfsfp))
932 perror("read_sysfs_float(): Failed to close dir");
934 goto error_free;
937 if (fclose(sysfsfp))
938 ret = -errno;
940 error_free:
941 free(temp);
943 return ret;
947 * read_sysfs_string() - read a string from file
948 * @filename: name of file to read from
949 * @basedir: the sysfs directory in which the file is to be found
950 * @str: output the read string
952 * Returns a value >= 0 on success, otherwise a negative error code.
954 int read_sysfs_string(const char *filename, const char *basedir, char *str)
956 int ret = 0;
957 FILE *sysfsfp;
958 char *temp = malloc(strlen(basedir) + strlen(filename) + 2);
960 if (!temp) {
961 fprintf(stderr, "Memory allocation failed");
962 return -ENOMEM;
965 ret = sprintf(temp, "%s/%s", basedir, filename);
966 if (ret < 0)
967 goto error_free;
969 sysfsfp = fopen(temp, "r");
970 if (!sysfsfp) {
971 ret = -errno;
972 goto error_free;
975 errno = 0;
976 if (fscanf(sysfsfp, "%s\n", str) != 1) {
977 ret = errno ? -errno : -ENODATA;
978 if (fclose(sysfsfp))
979 perror("read_sysfs_string(): Failed to close dir");
981 goto error_free;
984 if (fclose(sysfsfp))
985 ret = -errno;
987 error_free:
988 free(temp);
990 return ret;