Linux Mdev

[=>!]path

hda 0:0 660 =drives/                    # 将hda移动到drives目录
hdb 0:0 660 =cdrom                      # 将hdb命名为cdrom
tty[a-z] 0:0 660 !                      # 利用!阻止创建设备节点
([hs]d[a-z])            root:disk       660 >disk/%1/0
([hs]d[a-z])([0-9]+)    root:disk       660 >disk/%1/%2
mmcblk([0-9]+)          root:disk       660 >disk/mmc/%1/0
mmcblk([0-9]+)p([0-9]+) root:disk       660 >disk/mmc/%1/%2
(tun|tap)               root:network    660 >net/%1

[@|$|*]<command>

#if DEBUG_LVL >= 1
# define dbg1(...) do { if (G.verbose) bb_error_msg(__VA_ARGS__); } while(0)
#else
# define dbg1(...) ((void)0)
#endif
#if DEBUG_LVL >= 2
# define dbg2(...) do { if (G.verbose >= 2) bb_error_msg(__VA_ARGS__); } while(0)
#else
# define dbg2(...) ((void)0)
#endif
#if DEBUG_LVL >= 3
# define dbg3(...) do { if (G.verbose >= 3) bb_error_msg(__VA_ARGS__); } while(0)
#else
# define dbg3(...) ((void)0)
#endif

#define G (*(struct globals*)&bb_common_bufsiz1)

// <platform.h>
#define ALIGNED(m) __attribute__ ((__aligned__(m)))
// libbb/message.c
char bb_common_bufsiz1[COMMON_BUFSIZE] ALIGNED(sizeof(long long));

// <libbb.h>
extern char bb_common_bufsiz1[COMMON_BUFSIZE];
#ifndef BUFSIZ
# define BUFSIZ 4096
enum {
    COMMON_BUFSIZE = (BUFSIZ >= 256 * sizeof(void*) ? BUFSIZ + 1 :
                      256 * sizeof(void*))
};

void FAST_FUNC bb_error_msg(const char *s, ...)
{
    va_list p;

    va_start(p, s);
    bb_verror_msg(s, p, NULL);
    va_end(p);
}

/* FAST_FUNC is a qualifier which (possibly) makes function call faster
 * and/or smaller by using modified ABI. It is usually only needed
 * on non-static, busybox internal functions. Recent versions of gcc
 * optimize statics automatically. FAST_FUNC on static is required
 * only if you need to match a function pointer's type */
#if __GNUC_PREREQ(3,0) && defined(i386) /* || defined(__x86_64__)? */
/* stdcall makes callee to pop arguments from stack, not caller */
# define FAST_FUNC __attribute__((regparm(3),stdcall))
/* #elif ... - add your favorite arch today! */
#else
# define FAST_FUNC
#endif

 1: void FAST_FUNC bb_verror_msg(const char *s, va_list p, const char* strerr)
 2: {
 3:     char *msg, *msg1;
 4:     int applet_len, strerr_len, msgeol_len, used;
 5: 
 6:     if (!logmode)
 7:         return;
 8: 
 9:     if (!s) /* nomsg[_and_die] uses NULL fmt */
10:         s = ""; /* some libc don't like printf(NULL) */
11: 
12:     used = vasprintf(&msg, s, p);
13:     if (used < 0)
14:         return;
15: 
16:     /* This is ugly and costs +60 bytes compared to multiple
17:      * fprintf's, but is guaranteed to do a single write.
18:      * This is needed for e.g. httpd logging, when multiple
19:      * children can produce log messages simultaneously. */
20: 
21:     applet_len = strlen(applet_name) + 2; /* "applet: " */
22:     strerr_len = strerr ? strlen(strerr) : 0;
23:     msgeol_len = strlen(msg_eol);
24:     /* can't use xrealloc: it calls error_msg on failure,
25:      * that may result in a recursion */
26:     /* +3 is for ": " before strerr and for terminating NUL */
27:     msg1 = realloc(msg, applet_len + used + strerr_len + msgeol_len + 3);
28:     if (!msg1) {
29:         msg[used++] = '\n'; /* overwrites NUL */
30:         applet_len = 0;
31:     } else {
32:         msg = msg1;
33:         /* TODO: maybe use writev instead of memmoving? Need full_writev? */
34:         memmove(msg + applet_len, msg, used);
35:         used += applet_len;
36:         strcpy(msg, applet_name);
37:         msg[applet_len - 2] = ':';
38:         msg[applet_len - 1] = ' ';
39:         if (strerr) {
40:             if (s[0]) { /* not perror_nomsg? */
41:                 msg[used++] = ':';
42:                 msg[used++] = ' ';
43:             }
44:             strcpy(&msg[used], strerr);
45:             used += strerr_len;
46:         }
47:         strcpy(&msg[used], msg_eol);
48:         used += msgeol_len;
49:     }
50: 
51:     if (logmode & LOGMODE_STDIO) {
52:         fflush_all();
53:         full_write(STDERR_FILENO, msg, used);
54:     }
55: #if ENABLE_FEATURE_SYSLOG
56:     if (logmode & LOGMODE_SYSLOG) {
57:         syslog(LOG_ERR, "%s", msg + applet_len);
58:     }
59: #endif
60:     free(msg);
61: }

typedef int FAST_FUNC (*fileAction)(const char *fileName,
                                    struct stat *statbuf,
                                    void* userData,
                                    int depth);
typedef int FAST_FUNC (*dirAction)(const char *fileName,
                                   struct stat *statbuf,
                                   void* userData,
                                   int depth);

int FAST_FUNC recursive_action(const char *fileName,
                               unsigned flags,
                               fileAction,
                               dirAction,
                               void* userData,
                               unsigned depth);

static void make_device(char *device_name, char *path, int operation);

#if ENABLE_FEATURE_BUFFERS_GO_ON_STACK
#define RESERVE_CONFIG_BUFFER(buffer,len)  char buffer[len]
#define RESERVE_CONFIG_UBUFFER(buffer,len) unsigned char buffer[len]
#define RELEASE_CONFIG_BUFFER(buffer)      ((void)0)
#else
#if ENABLE_FEATURE_BUFFERS_GO_IN_BSS
#define RESERVE_CONFIG_BUFFER(buffer,len)  static          char buffer[len]
#define RESERVE_CONFIG_UBUFFER(buffer,len) static unsigned char buffer[len]
#define RELEASE_CONFIG_BUFFER(buffer)      ((void)0)
#else
#define RESERVE_CONFIG_BUFFER(buffer,len)  char *buffer = xmalloc(len)
#define RESERVE_CONFIG_UBUFFER(buffer,len) unsigned char *buffer = xmalloc(len)
#define RELEASE_CONFIG_BUFFER(buffer)      free(buffer)
#endif
#endif

RESERVE_CONFIG_BUFFER(temp, PATH_MAX + SCRATCH_SIZE);
INIT_G();
#if ENABLE_FEATURE_MDEV_CONF
    G.filename = "/etc/mdev.conf";
#endif

umask(0);                               // 设置umask
xchdir("/dev");                         // 切换到目录/dev

if (access("/sys/class/block", F_OK) != 0) {
    /* Scan obsolete /sys/block only if /sys/class/block
     * doesn't exist. Otherwise we'll have dupes.
     * Also, do not complain if it doesn't exist.
     * Some people configure kernel to have no blockdevs.
     */
    recursive_action("/sys/block",
                     ACTION_RECURSE | ACTION_FOLLOWLINKS | ACTION_QUIET,
                     fileAction, dirAction, temp, 0);
}
recursive_action("/sys/class",
                 ACTION_RECURSE | ACTION_FOLLOWLINKS,
                 fileAction, dirAction, temp, 0);