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    Annotation of /tags/mkinitrd-6_1_8/nash/name_to_dev_t.c

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    Revision 916 - (hide annotations) (download)
    Wed Oct 28 00:17:50 2009 UTC (14 years, 7 months ago) by niro
    File MIME type: text/plain
    File size: 3437 byte(s) 
    tagged 'mkinitrd-6_1_8'
    1 niro 532 #include <stdlib.h>
    2     #include <string.h>
    3     #include <unistd.h>
    4     #include <ctype.h>
    5     #include <stdio.h>
    6     #include <fcntl.h>
    7     #include <sys/stat.h>
    8    
    9     #include "name_to_dev_t.h"
    10    
    11     static dev_t
    12     try_name(char *name, int part)
    13     {
    14     char path[64];
    15     char buf[32];
    16     int range;
    17     dev_t res;
    18     char *s;
    19     int len;
    20     int fd;
    21     unsigned int maj, min;
    22     struct stat sb;
    23    
    24     /* read device number from .../dev */
    25    
    26     sprintf(path, "/sys/block/%s/dev", name);
    27     fd = open(path, O_RDONLY);
    28     if (fd < 0)
    29     goto fail;
    30     len = read(fd, buf, 32);
    31     close(fd);
    32     if (len <= 0 || len == 32 || buf[len - 1] != '\n')
    33     goto fail;
    34     buf[len - 1] = '\0';
    35     if (sscanf(buf, "%u:%u", &maj, &min) != 2)
    36     goto fail;
    37     res = makedev(maj, min);
    38     if (maj != major(res) || min != minor(res))
    39     goto fail;
    40    
    41     /* if it's there and we are not looking for a partition - that's it */
    42     if (!part)
    43     return res;
    44    
    45     /* otherwise read range from .../range */
    46     snprintf(path, 64, "/sys/block/%s/range", name);
    47     fd = open(path, O_RDONLY);
    48     if (fd < 0)
    49     goto fail;
    50     len = read(fd, buf, 32);
    51     close(fd);
    52     if (len <= 0 || len == 32 || buf[len - 1] != '\n')
    53     goto fail;
    54     buf[len - 1] = '\0';
    55     range = strtoul(buf, &s, 10);
    56     if (*s)
    57     goto fail;
    58    
    59     /* if partition is within range - we got it */
    60     if (part < range)
    61     return res + part;
    62     fail:
    63     sprintf(path, "/dev/%s", name);
    64     if (!stat(path, &sb)) {
    65     if (S_ISBLK(sb.st_mode))
    66     return sb.st_rdev;
    67     }
    68     return 0;
    69     }
    70    
    71     /*
    72     * Convert a name into device number. We accept the following variants:
    73     *
    74     * 1) device number in hexadecimal represents itself
    75     * 2) /dev/nfs represents Root_NFS (0xff)
    76     * 3) /dev/<disk_name> represents the device number of disk
    77     * 4) /dev/<disk_name><decimal> represents the device number
    78     * of partition - device number of disk plus the partition number
    79     * 5) /dev/<disk_name>p<decimal> - same as the above, that form is
    80     * used when disk name of partitioned disk ends on a digit.
    81     *
    82     * If name doesn't have fall into the categories above, we return 0.
    83     * sysfs is used to check if something is a disk name - it has
    84     * all known disks under bus/block/devices. If the disk name
    85     * contains slashes, name of driverfs node has them replaced with
    86     * bangs. try_name() does the actual checks, assuming that sysfs
    87     * is mounted on /sys.
    88     *
    89     * Note that cases (1) and (2) are already handled by the kernel,
    90     * so we can ifdef them out, provided that we check real-root-dev
    91     * first.
    92     */
    93    
    94     dev_t
    95     name_to_dev_t(char *name)
    96     {
    97     char s[32];
    98     char *p;
    99     dev_t res = 0;
    100     int part;
    101    
    102     if (strncmp(name, "/dev/", 5) != 0) {
    103     #if 1 /* kernel used to do this */
    104     unsigned maj, min;
    105    
    106     if (sscanf(name, "%u:%u", &maj, &min) == 2) {
    107     res = makedev(maj, min);
    108     if (maj != major(res) || min != minor(res))
    109     return 0;
    110     } else {
    111     res = strtoul(name, &p, 16);
    112     if (*p)
    113     return 0;
    114     }
    115     #endif
    116     return res;
    117     }
    118    
    119     name += 5;
    120    
    121     #if 1 /* kernel used to do this */
    122     if (strcmp(name, "nfs") == 0)
    123     return makedev(0, 255);
    124     #endif
    125     if (strchr(name, '/')) {
    126     res = try_name(name, 1);
    127     if (res)
    128     return res;
    129     }
    130    
    131     if (strlen(name) > 31)
    132     return 0;
    133     strcpy(s, name);
    134     for (p = s; *p; p++)
    135     if (*p == '/')
    136     *p = '!';
    137     res = try_name(s, 0);
    138     if (res)
    139     return res;
    140    
    141     while (p > s && isdigit(p[-1]))
    142     p--;
    143     if (p == s || !*p || *p == '0')
    144     return 0;
    145     part = strtoul(p, NULL, 10);
    146     *p = '\0';
    147     res = try_name(s, part);
    148     if (res)
    149     return res;
    150    
    151     if (p < s + 2 || !isdigit(p[-2]) || p[-1] != 'p')
    152     return 0;
    153     p[-1] = '\0';
    154     return try_name(s, part);
    155     }