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o Ok, this seems to be a much better method for caching valid

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devices based on /proc/devices
   + The dev_mgr structure now has a 256 element char array that is
     initially all 0s
   + When a match is found, the array element corresponding to the major
     number of the match is set to a non-zero value
   + to check for a match, all one has to do is check that the array
     element at the major number in question is non-zero.
 o I'm wondering if we should do this with bitwise operators instead?  Does
   anyone expect the major numbers to grow larger than 8-bits?
This commit is contained in:
AJ Lewis 2001-08-21 20:40:37 +00:00
parent 83b2c0d30a
commit a53d451f30
1 changed files with 19 additions and 25 deletions
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42
lib/dev-mgr/dev-manager.c
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@ -49,6 +49,7 @@
#define LOCAL_EPARAM 1 #define LOCAL_EPARAM 1
#define LOCAL_CHECK_NAME 2 #define LOCAL_CHECK_NAME 2
#define LOCAL_DEVICE_TYPE_INVALID 3 #define LOCAL_DEVICE_TYPE_INVALID 3
#define NUMBER_OF_MAJORS 256
static const char *device_names[] = { static const char *device_names[] = {
"ide", /* IDE disk */ "ide", /* IDE disk */
@ -73,20 +74,13 @@ struct dev_i {
struct dev_i *next; struct dev_i *next;
}; };
/* temporary structure - will replace with something smarter later */
struct dev_n {
int major;
struct dev_n *next;
};
struct dev_mgr { struct dev_mgr {
/* everything is allocated from this pool */ /* everything is allocated from this pool */
struct pool *pool; struct pool *pool;
int has_scanned; int has_scanned;
/* linked list of valid major numbers */ char valid_majors[NUMBER_OF_MAJORS];
struct dev_n *dev_list;
/* hash table */ /* hash table */
int num_slots; int num_slots;
@ -273,7 +267,6 @@ static struct dev_i *_add_named_device(struct dev_mgr *dm, const char *devpath)
struct dev_i *dev = NULL; struct dev_i *dev = NULL;
struct stat stat_b; struct stat stat_b;
/* FIXME: move lvm_check_dev into this file */
if ((stat(devpath, &stat_b) == -1) || _check_dev(dm, &stat_b)) if ((stat(devpath, &stat_b) == -1) || _check_dev(dm, &stat_b))
goto out; goto out;
@ -448,25 +441,25 @@ static int _check_dev(struct dev_mgr *dm, struct stat *stat_b)
else if ( ! S_ISBLK(stat_b->st_mode)) else if ( ! S_ISBLK(stat_b->st_mode))
ret = -LOCAL_CHECK_NAME; ret = -LOCAL_CHECK_NAME;
else { else {
for(node = dm->dev_list; node != NULL; node = node->next) if (dm->valid_majors[seek_major])
if (node->major == seek_major)
ret = 0; ret = 0;
} }
return ret; return ret;
} }
/* Caches /proc/device info and /* Caches /proc/device info and returns the number of block devices found
returns the number of block devices found in /proc/devices */ in /proc/devices */
static int _scan_proc_dev(struct dev_mgr *dm) static int _scan_proc_dev(struct dev_mgr *dm)
{ {
char line[80]; char line[80];
FILE *procdevices = NULL; FILE *procdevices = NULL;
int ret = 0; int ret = 0;
int i, j = 0; int i, j = 0;
int line_major = 0; int line_maj = 0;
int blocksection = 0; int blocksection = 0;
struct dev_n * dev_node= NULL; struct dev_n * dev_node= NULL;
int dev_len = 0;
if ((procdevices = fopen("/proc/devices", "r")) != NULL) { if ((procdevices = fopen("/proc/devices", "r")) != NULL) {
while (fgets(line, 80, procdevices) != NULL) { while (fgets(line, 80, procdevices) != NULL) {
@ -475,8 +468,8 @@ static int _scan_proc_dev(struct dev_mgr *dm)
i++; i++;
/* If its not a number it may be name of section */ /* If its not a number it may be name of section */
line_major = atoi(((char *) (line + i))); line_maj = atoi(((char *) (line + i)));
if (line_major == 0) { if (line_maj == 0) {
blocksection = (line[i] == 'B') ? 1 : 0; blocksection = (line[i] == 'B') ? 1 : 0;
continue; continue;
} }
@ -490,17 +483,18 @@ static int _scan_proc_dev(struct dev_mgr *dm)
while (line[i] == ' ' && line[i] != '\0') while (line[i] == ' ' && line[i] != '\0')
i++; i++;
/* Go through the valid device names and if there is a
match, set the array member corresponding to the
major number to !0 */
for (j = 0; device_names[j] != NULL; j++) { for (j = 0; device_names[j] != NULL; j++) {
if (strlen(device_names[j])
<= strlen(line + i)) { dev_len = strlen(device_names[j]);
if (dev_len <= strlen(line + i)) {
if (strncmp (device_names[j], if (strncmp (device_names[j],
line + i, line + i,
strlen(device_names[j])) == 0) { dev_len) == 0) {
dev_node = pool_alloc(dm->pool,
sizeof(*dev_node)); dm->valid_majors[line_maj]='1';
dev_node->major = line_major;
dev_node->next=dm->dev_list;
dm->dev_list = dev_node;
ret++; ret++;
break; break;
} }