xattr-util.c

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/xattr.h>
#include <linux/xattr.h>
#include <sys/types.h>

#define CMDLS "-l"
#define CMDSET "-s"
#define CMDGET "-g"
#define CMDREM "-r"
#define USAGE_GENERAL "<command> <opt args> <path>"
#define USAGE_LIST CMDLS " <path>"
#define USAGE_SET CMDSET " <Attr Name> <Attr Value> <path>"
#define USAGE_GET CMDGET " <Attr Name> <path>"
#define USAGE_REM CMDREM " <Attr Name> <path>"

#ifdef linux
/* Linux is missing ENOATTR error, using ENODATA instead */
#define ENOATTR ENODATA
#endif

/* Add namespace defintion for older kernels. Normally included in linux/xattr.h */
#ifndef XATTR_USER_PREFIX
#define XATTR_USER_PREFIX "user."
#define XATTR_USER_PREFIX_LEN (sizeof (XATTR_USER_PREFIX) - 1)
#endif

static void printUsageGeneral(char* pgmName){
  fprintf(stderr, "Usage: %s %s\n",
    pgmName, USAGE_GENERAL);
}

static void printUsageList(char* pgmName){
  fprintf(stderr, "Usage: %s %s\n",
    pgmName, USAGE_LIST);
}

static void printUsageSet(char* pgmName){
  fprintf(stderr, "Usage: %s %s\n",
    pgmName, USAGE_SET);
}

static void printUsageGet(char* pgmName){
  fprintf(stderr, "Usage: %s %s\n",
    pgmName, USAGE_GET);
}

static void printUsageRem(char* pgmName){
  fprintf(stderr, "Usage: %s %s\n",
    pgmName, USAGE_REM);
}

int main(int argc, char* argv[]){

    /* Local vars */
  char* lst = NULL;
  char* chr = NULL;
  char* start = NULL;
  char* tmpstr = NULL;
  char* tmpval = NULL;
  ssize_t cnt = 0;
  ssize_t lstsize = 0;
  ssize_t valsize = 0;

    /* Check base input */
  if(argc < 2){
    printUsageGeneral(argv[0]);
    exit(EXIT_FAILURE);
  }

    /* Parse Command */
  if(!strcmp(argv[1], CMDLS)){
  /* List Case */
  /* Check proper input */
    if(argc != 3){
      printUsageList(argv[0]);
      exit(EXIT_FAILURE);
    }
  /* Call xattr list to get size */
    lstsize = listxattr(argv[2], NULL, 0);
    if(lstsize < 0){
      perror("listxattr error");
      fprintf(stderr, "path  = %s\n", argv[2]);
      exit(EXIT_FAILURE);
    }
  /* Malloc space for list items */
    lst = malloc(sizeof(*lst)*lstsize);
    if(!lst){
      perror("malloc of 'lst' error");
      exit(EXIT_FAILURE);
    }
  /* Call xattr list to get data */
    lstsize = listxattr(argv[2], lst, lstsize);
    if(lstsize < 0 || !lst){
      perror("listxattr error");
      fprintf(stderr, "path  = %s\n", argv[2]);
      exit(EXIT_FAILURE);
    }
  /* Tokenize null seperated array on \0 */
    chr = start = lst;
    cnt = 0;
    while(cnt < lstsize){
      /* Print attribute names, one per line */
      fprintf(stdout, "%s\n", start);
      while(*chr != '\0'){
        chr++;
        cnt++;
      }
      start = ++chr;
      cnt++;
    }
  }
  else if(!strcmp(argv[1], CMDSET)){
  /* Set Case */
  /* Check proper input */
    if(argc != 5){
      printUsageSet(argv[0]);
      exit(EXIT_FAILURE);
    }
  /* Append necessary 'user.' namespace prefix to beginning of name string */
    tmpstr = malloc(strlen(argv[2]) + XATTR_USER_PREFIX_LEN + 1);
    if(!tmpstr){
      perror("malloc of 'tmpstr' error");
      exit(EXIT_FAILURE);
    }
    strcpy(tmpstr, XATTR_USER_PREFIX);
    strcat(tmpstr, argv[2]);
  /* Set attribute */
    if(setxattr(argv[4], tmpstr, argv[3], strlen(argv[3]), 0)){
      perror("setxattr error");
      fprintf(stderr, "path  = %s\n", argv[4]);
      fprintf(stderr, "name  = %s\n", tmpstr);
      fprintf(stderr, "value = %s\n", argv[3]);
      fprintf(stderr, "size  = %zd\n", strlen(argv[3]));
      exit(EXIT_FAILURE);
    }
  /* Cleanup */
    free(tmpstr);
  }
  else if(!strcmp(argv[1], CMDGET)){
  /* Get Case */
  /* Check proper input */
    if(argc != 4){
      printUsageGet(argv[0]);
      exit(EXIT_FAILURE);
    }
  /* Append necessary 'user.' namespace prefix to beginning of name string */
    tmpstr = malloc(strlen(argv[2]) + XATTR_USER_PREFIX_LEN + 1);
    if(!tmpstr){
      perror("malloc of 'tmpstr' error");
      exit(EXIT_FAILURE);
    }
    strcpy(tmpstr, XATTR_USER_PREFIX);
    strcat(tmpstr, argv[2]);
  /* Get attribute value size */
    valsize = getxattr(argv[3], tmpstr, NULL, 0);
    if(valsize < 0){
      if(errno == ENOATTR){
        fprintf(stdout, "No %s attribute set on %s\n", tmpstr, argv[3]);
        free(tmpstr);
        return EXIT_SUCCESS;
      }
      else{
        perror("getxattr error");
        fprintf(stderr, "path  = %s\n", argv[3]);
        fprintf(stderr, "name  = %s\n", tmpstr);
        fprintf(stderr, "value = %s\n", "NULL");
        fprintf(stderr, "size  = %zd\n", valsize);
        exit(EXIT_FAILURE);
      }
    }
  /* Malloc Value Space */
    tmpval = malloc(sizeof(*tmpval)*(valsize+1));
    if(!tmpval){
      perror("malloc of 'tmpval' error");
      exit(EXIT_FAILURE);
    }
  /* Get attribute value */
    valsize = getxattr(argv[3], tmpstr, tmpval, valsize);
    if(valsize < 0){
      if(errno == ENOATTR){
        fprintf(stdout, "No %s attribute set on %s\n", tmpstr, argv[3]);
        free(tmpval);
        free(tmpstr);
        return EXIT_SUCCESS;
      }
      else{
        perror("getxattr error");
        fprintf(stderr, "path  = %s\n", argv[3]);
        fprintf(stderr, "name  = %s\n", tmpstr);
        fprintf(stderr, "value = %s\n", tmpval);
        fprintf(stderr, "size  = %zd\n", valsize);
        exit(EXIT_FAILURE);
      }
    }

  /* Print Value */
    tmpval[valsize] = '\0';
    fprintf(stdout, "%s = %s\n", tmpstr, tmpval);

  /* Clean Up */
    free(tmpval);
    free(tmpstr);
  }
  else if(!strcmp(argv[1], CMDREM)){
  /* Remove Case */
  /* Check proper input */
    if(argc != 4){
      printUsageRem(argv[0]);
      exit(EXIT_FAILURE);
    }
  /* Append necessary 'user.' namespace prefix to beginning of name string */
    tmpstr = malloc(strlen(argv[2]) + XATTR_USER_PREFIX_LEN + 1);
    if(!tmpstr){
      perror("malloc of 'tmpstr' error");
      exit(EXIT_FAILURE);
    }
    strcpy(tmpstr, XATTR_USER_PREFIX);
    strcat(tmpstr, argv[2]);
  /* Remove Attr */
    if(removexattr(argv[3], tmpstr)){
      if(errno == ENOATTR){
        fprintf(stdout, "No %s attribute set on %s\n", tmpstr, argv[3]);
        free(tmpstr);
        return EXIT_SUCCESS;
      }
      else{
        perror("removexattr error");
        fprintf(stderr, "path  = %s\n", argv[3]);
        fprintf(stderr, "name  = %s\n", tmpstr);
        exit(EXIT_FAILURE);
      }
    }
  /* Cleanup */
    free(tmpstr);
  }
  else{
  /* Bad Case */
    fprintf(stderr, "Unrecognized option\n");
    exit(EXIT_FAILURE);
  }

  return EXIT_SUCCESS;
}