AIX:AHAFS ahamoddir.c
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/* * mon_moddir_event.c * * This program monitors for modifications to a file specified by the user. * Event occurrences are printed to the user. If the file being monitored is * removed or renamed, it will be recreated and monitoring will continue. * * If the filesystem containing the file is unmounted, or the file itself is * overmounted, monitoring will cease and the program will exit. * * This program assumes the AIX Event Infrastructure file system has been * mounted on /aha. To mount it, run: * mkdir /aha * mount -v ahafs /aha /aha * */
#include <stdio.h> #include <sys/poll.h> #include <sys/pollset.h> #include <fcntl.h> #include <string.h> #include <errno.h> #include <sys/time.h> #include <sys/select.h> #include <sys/types.h> #include <sys/stat.h> #include <ctype.h> #include <libgen.h> #include <usersec.h> #include <sys/ahafs_evProds.h>
#define RDWR_BUF_SIZE 4096
int sequence_num; char *objName; ushort objMode; uid_t objUid; gid_t objGid;
/* NAME: skip_lines
* PURPOSE: Skips a specified number of lines in the buffer passed in.
* PARAMETERS:
* p - Address of the pointer to the head of the buffer
* n - The number of lines to skip
* RETURNS:
* Total number of lines skipped
*/
int
skip_lines(char **p, int n)
{
int lines = 0;
while(n > 0)
{
*p = strchr(*p, '\n');
if(!p)
return(lines);
(*p)++;
n--;
lines++;
}
return(lines); }
/* NAME: print_op
* PURPOSE: Prints a string indicating what monitored file operation triggered
* the event occurrence.
* PARAMETERS:
* evp_rc - The return code from RC_FROM_EVPROD
* RETURNS:
* Nothing.
*/
void
print_op(int evp_rc)
{
if(evp_rc == AHAFS_MODDIR_CREATE)
printf("File created.");
else if(evp_rc == AHAFS_MODDIR_UNMOUNT)
printf("Filesystem unmounted.");
else if(evp_rc == AHAFS_MODDIR_REMOVE)
printf("File removed.");
else if(evp_rc == AHAFS_MODDIR_REMOVE_SELF)
printf("File renamed.");
else
printf("Unknown file op: %d", evp_rc);
}
/* NAME: mk_subdirs
* PURPOSE: Creates necessary subdirectories in the AIX Event Infrastructure
* file system for monitoring the object specified.
* RETURNS:
* Return code from mkdir call
*/
int
mk_subdirs()
{
char cmd[2048];
char *p;
/* Strip off the monitor file name */ p = strrchr(objName, '/');
if(p == NULL)
return(0);
sprintf(cmd, "/usr/bin/mkdir -p /aha/fs/modDir.monFactory/"); strncat(cmd, objName, (p - objName)); return(system(cmd)); }
/* NAME: parse_data
* PURPOSE: This function will parse the event occurrence data and take
* corrective action if necessary.
* PARAMETERS:
* buf - A pointer to the buffer containing the event occurrence data
* err - Indicates if the previous select() call returned an error
* (a different parsing format is required).
* RETURNS:
* 0 - No corrective action needed.
* 1 - Corrective action taken, monitoring must be restarted.
* 2 - Unrecoverable error in parsing
*/
int
parse_data(char *buf, int err)
{
int rc = 0, evp_rc, recreate = 0;
char *p;
time_t sec, nsec;
int seq_num;
pid_t pid;
uid_t uid, gid;
gid_t luid;
char curTm[64], cmd[64];
char uname[64], lname[64], gname[64];
p = buf;
/* Check for BUF_WRAP */
if(strncmp(buf, "BUF_WRAP", strlen("BUF_WRAP")) == 0)
{
printf("Buffer wrap detected, Some event occurrences lost!\n");
return(0);
}
/* Since we are using the default buffer size (4K), and have specified
* INFO_LVL=1, we won't see any EVENT_OVERFLOW conditions. Applications
* should check for this keyword if they are using an INFO_LVL of 2 or
* higher, and have a buffer size of <= 4K
*/
/* Skip "BEGIN_EVENT_INFO" header */
if(skip_lines(&p, 1) != 1)
return(2);
/* Get timestamp and sequence number. */
if(sscanf(p,"TIME_tvsec=%ld\nTIME_tvnsec=%ld\nSEQUENCE_NUM=%d\n",
&sec, &nsec, &seq_num) == 3)
{
ctime_r(&sec, curTm);
if(skip_lines(&p, 3) != 3)
return(2);
printf("Time : %s", curTm);
printf("Seq num : %d", seq_num);
if(seq_num != sequence_num)
printf(" (%d duplicates)\n", (seq_num - sequence_num));
else
printf("\n");
sequence_num = seq_num + 1;
}
else
return(2);
if(err)
{
/* We just expect to see the RC_FROM_EVPROD and the "END_EVENT_DATA"
* footer after the timestamp and sequence number in the error case */
if(sscanf(p, "RC_FROM_EVPROD=%d\nEND_EVENT_DATA", &evp_rc) == 1)
{
printf("Error in event monitoring: %d.", evp_rc);
if(evp_rc == ENODEV)
{
/* Object being monitored doesn't exist, recreate it */
printf(" Recreating object.\n");
recreate = 1;
}
else
{
/* Some other error occurred which we can't correct */
printf(" Unable to recover.\n");
rc = 2;
}
}
else
return(2);
}
else
{
/* Collect user and process info */
if(sscanf(p,
"PID=%ld\nUID=%ld\nUID_LOGIN=%ld\nGID=%ld\nPROG_NAME=%s\n",
&pid, &uid, &luid, &gid, cmd) == 5)
{
strcpy(uname, IDtouser(uid));
strcpy(lname, IDtouser(luid));
strcpy(gname, IDtogroup(gid));
printf("Process ID : %d\n", pid);
printf("User Info : userName=%s, loginName=%s, groupName=%s\n",
uname, lname, gname);
printf("Program Name : %s\n", cmd);
/* Get the RC_FROM_EVPROD */
if(skip_lines(&p, 5) != 5)
return(2);
if(sscanf(p, "RC_FROM_EVPROD=%d\nEND_EVENT_DATA", &evp_rc) == 1)
{
print_op(evp_rc);
switch(evp_rc)
{
case AHAFS_MODDIR_CREATE:
/* Recreate the object */
printf(" A file has been created in the directory.\n\n");
break;
case AHAFS_MODDIR_REMOVE:
/* Unrecoverable "unavailable" events. */
printf(" A file has been removed in the directory.\n\n");
break;
default:
printf(" No action required.\n\n");
}
}
else
return(2);
}
else
return(2);
}
if(recreate)
{
int fd;
fd = creat(objName, objMode);
if(fd != -1)
{
rc = chown(objName, objUid, objGid);
}
if((fd == -1) || rc)
{
perror("Error recreating object");
rc = 2;
}
else
rc = 1;
}
return(rc); }
int
main(int argc, char *argv[])
{
int c, i = 0;
int fd, rc, bytes, err=0, restart;
fd_set readfds;
char monFile[PATH_MAX];
char resultData[RDWR_BUF_SIZE];
char monFileWrStr[RDWR_BUF_SIZE];
struct stat statbuf;
if(argc != 2)
{
printf("Usage: %s <full path to file to monitor>\n", argv[0]);
printf(" Example: %s /etc/passwd\n", argv[0]);
return(-1);
}
/* Create monitor file name for object */
objName = argv[1];
sprintf(monFile, "/aha/fs/modDir.monFactory");
if((strlen(monFile) + strlen(objName) + 5) > PATH_MAX)
{
fprintf(stderr, "Error: Cannot monitor object, path name too long\n");
return(ENAMETOOLONG);
}
/* Make the necessary subdirectories for the monitor file */
if(rc = mk_subdirs())
return(rc);
strcat(monFile, objName); strcat(monFile, ".mon");
/* Save off the mode and ownership of monitored object */
if(stat(objName, &statbuf) < 0)
{
perror("Error stating file");
return(errno);
}
objGid = statbuf.st_gid; objUid = statbuf.st_uid; objMode = statbuf.st_mode;
open: restart = 0; sequence_num = 0;
/* Open the monitor file, creating it if necessary */
fd = open(monFile, O_CREAT|O_RDWR);
if(fd < 0)
{
perror("Error opening monitor file");
return(errno);
}
/* Write out the monitoring specifications.
* In this case, we are monitoring for a state change event type
* (modFile):
* CHANGED=YES
* We will be waiting in select call, rather than a read:
* WAIT_TYPE=WAIT_IN_SELECT
* we only want minimal information:
* INFO_LVL=1
*/
sprintf(monFileWrStr, "CHANGED=YES;WAIT_TYPE=WAIT_IN_SELECT;INFO_LVL=1");
rc = write(fd, monFileWrStr, strlen(monFileWrStr)+1);
if (rc < 0)
{
perror("Error writing to monitor file");
return(errno);
}
/* Keep monitoring for event occurrences until stopped */
while(1)
{
/* Initialize the set */
FD_ZERO(&readfds);
FD_SET(fd, &readfds);
err = 0;
rc = select(fd+1, &readfds, NULL, NULL, NULL);
if (rc <= 0)
{
/* All errors in event monitoring will cause select to return
* EBADF. Read to see if any additional data is available.
*/
perror("Error issuing select");
err = 1;
}
bytes = pread(fd, resultData, RDWR_BUF_SIZE, 0);
if(bytes < 0)
perror("Error reading monitor file");
else if(bytes == 0)
fprintf(stderr,
"Error reading monitor file. No data to be read\n");
else
restart = parse_data(resultData, err);
if(restart == 2)
break;
if(restart)
{
close(fd);
goto open;
}
}
close(fd);
return(err);
}