github.com/afumu/libc@v0.0.6/musl/src/passwd/nscd_query.c (about)

     1  #include <sys/socket.h>
     2  #include <byteswap.h>
     3  #include <unistd.h>
     4  #include <stdio.h>
     5  #include <string.h>
     6  #include <errno.h>
     7  #include <limits.h>
     8  #include "nscd.h"
     9  
    10  static const struct {
    11  	short sun_family;
    12  	char sun_path[21];
    13  } addr = {
    14  	AF_UNIX,
    15  	"/var/run/nscd/socket"
    16  };
    17  
    18  FILE *__nscd_query(int32_t req, const char *key, int32_t *buf, size_t len, int *swap)
    19  {
    20  	size_t i;
    21  	int fd;
    22  	FILE *f = 0;
    23  	int32_t req_buf[REQ_LEN] = {
    24  		NSCDVERSION,
    25  		req,
    26  		strnlen(key,LOGIN_NAME_MAX)+1
    27  	};
    28  	struct msghdr msg = {
    29  		.msg_iov = (struct iovec[]){
    30  			{&req_buf, sizeof(req_buf)},
    31  			{(char*)key, strlen(key)+1}
    32  		},
    33  		.msg_iovlen = 2
    34  	};
    35  	int errno_save = errno;
    36  
    37  	*swap = 0;
    38  retry:
    39  	memset(buf, 0, len);
    40  	buf[0] = NSCDVERSION;
    41  
    42  	fd = socket(PF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0);
    43  	if (fd < 0) return NULL;
    44  
    45  	if(!(f = fdopen(fd, "r"))) {
    46  		close(fd);
    47  		return 0;
    48  	}
    49  
    50  	if (req_buf[2] > LOGIN_NAME_MAX)
    51  		return f;
    52  
    53  	if (connect(fd, (struct sockaddr*)&addr, sizeof(addr)) < 0) {
    54  		/* If there isn't a running nscd we simulate a "not found"
    55  		 * result and the caller is responsible for calling
    56  		 * fclose on the (unconnected) socket. The value of
    57  		 * errno must be left unchanged in this case.  */
    58  		if (errno == EACCES || errno == ECONNREFUSED || errno == ENOENT) {
    59  			errno = errno_save;
    60  			return f;
    61  		}
    62  		goto error;
    63  	}
    64  
    65  	if (sendmsg(fd, &msg, MSG_NOSIGNAL) < 0)
    66  		goto error;
    67  
    68  	if (!fread(buf, len, 1, f)) {
    69  		/* If the VERSION entry mismatches nscd will disconnect. The
    70  		 * most likely cause is that the endianness mismatched. So, we
    71  		 * byteswap and try once more. (if we already swapped, just
    72  		 * fail out)
    73  		 */
    74  		if (ferror(f)) goto error;
    75  		if (!*swap) {
    76  			fclose(f);
    77  			for (i = 0; i < sizeof(req_buf)/sizeof(req_buf[0]); i++) {
    78  				req_buf[i] = bswap_32(req_buf[i]);
    79  			}
    80  			*swap = 1;
    81  			goto retry;
    82  		} else {
    83  			errno = EIO;
    84  			goto error;
    85  		}
    86  	}
    87  
    88  	if (*swap) {
    89  		for (i = 0; i < len/sizeof(buf[0]); i++) {
    90  			buf[i] = bswap_32(buf[i]);
    91  		}
    92  	}
    93  
    94  	/* The first entry in every nscd response is the version number. This
    95  	 * really shouldn't happen, and is evidence of some form of malformed
    96  	 * response.
    97  	 */
    98  	if(buf[0] != NSCDVERSION) {
    99  		errno = EIO;
   100  		goto error;
   101  	}
   102  
   103  	return f;
   104  error:
   105  	fclose(f);
   106  	return 0;
   107  }