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diminuto_observation.c
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diminuto_observation.c
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/* vi: set ts=4 expandtab shiftwidth=4: */
/**
* @file
* @copyright Copyright 2019-2022 Digital Aggregates Corporation, Colorado, USA.
* @note Licensed under the terms in LICENSE.txt.
* @brief This is the implementation of the Observation feature.
* @author Chip Overclock <mailto:coverclock@diag.com>
* @see Diminuto <https://github.com/coverclock/com-diag-diminuto>
* @details
* This is the implementation of the Observation feature.
*/
#include "com/diag/diminuto/diminuto_observation.h"
#include "com/diag/diminuto/diminuto_types.h"
#include "com/diag/diminuto/diminuto_time.h"
#include "com/diag/diminuto/diminuto_frequency.h"
#include "com/diag/diminuto/diminuto_log.h"
#include <string.h>
#include <errno.h>
#include <stdlib.h>
#include <fcntl.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <alloca.h>
static const char SUFFIX[] = "-" "XXXXXX";
static const char TIMESTAMP[] = "-" "YYYYMMDD" "T" "HHMMSS" "Z" "UUUUUU";
FILE * diminuto_observation_create_generic(const char * path, char ** tempp, mode_t mode)
{
FILE * fp = (FILE *)0;
size_t length = 0;
char * temp = (char *)0;
int fd = -1;
int rc = -1;
do {
if (sizeof(SUFFIX) > sizeof(diminuto_path_t)) {
errno = E2BIG;
diminuto_perror("diminuto_observation_create_generic: sizeof");
break;
}
length = strlen(path);
if (length > (sizeof(diminuto_path_t) - sizeof(SUFFIX) - 1)) {
errno = ENAMETOOLONG;
diminuto_perror("diminuto_observation_create_generic: strlen");
break;
}
temp = (char *)malloc(length + sizeof(SUFFIX));
if (temp == (char *)0) {
diminuto_perror("diminuto_observation_create_generic: malloc");
break;
}
strcpy(temp, path);
strcat(temp, SUFFIX);
fd = mkstemp(temp);
if (fd < 0) {
diminuto_perror("diminuto_observation_create_generic: mkstemp");
break;
}
/*
* According to POSIX, the default file creation mask used
* by mkstemp(3) is 0600.
*/
rc = fchmod(fd, mode);
if (rc < 0) {
diminuto_perror("diminuto_observation_create_generic: fchmod");
break;
}
fp = fdopen(fd, "r+");
if (fp == (FILE *)0) {
diminuto_perror("diminuto_observation_create_generic: fdopen");
break;
}
*tempp = temp;
} while (0);
if (temp == (char *)0) {
/* Do nothing. */
} if (*tempp == temp) {
/* Do nothing. */
} else {
free(temp);
}
if (fp != (FILE *)0) {
/* Do nothing. */
} else if (fd < 0) {
/* Do nothing. */
} else if (close(fd) >= 0) {
/* Do nothing. */
} else {
diminuto_perror("diminuto_observation_create_generic: close");
}
return fp;
}
FILE * diminuto_observation_commit(FILE * fp, char ** tempp)
{
int rc = -1;
size_t length = 0;
char * path = (char *)0;
do {
length = strlen(*tempp);
if (!((sizeof(SUFFIX) < length) && (length < sizeof(diminuto_path_t)))) {
errno = ENAMETOOLONG;
diminuto_perror("diminuto_observation_commit: strlen");
break;
}
length += 1; /* Include terminating NUL. */
path = (char *)alloca(length); /* No error return. */
strncpy(path, *tempp, length);
path[length - sizeof(SUFFIX)] = '\0'; /* Truncate suffix. */
rc = fclose(fp);
if (rc != 0) {
diminuto_perror("diminuto_observation_commit: fclose");
break;
}
/*
* If fclose(3) succeeds but renameat(2) does not, we still return the
* original FILE pointer to indicate failure, even though it is no
* longer useful. We must do the fclose(3) prior to the renameat(2) to
* insure the renamed file is immediately accessible.
*/
rc = renameat(AT_FDCWD, *tempp, AT_FDCWD, path);
if (rc < 0) {
diminuto_perror("diminuto_observation_commit: renameat");
break;
}
free(*tempp);
*tempp = (char *)0;
fp = (FILE *)0;
} while (0);
return fp;
}
FILE * diminuto_observation_checkpoint(FILE * fp, char ** tempp)
{
FILE * result = (FILE *)0;
int rc = -1;
size_t length = 0;
char * path = (char *)0;
diminuto_sticks_t now = 0;
int year = 0;
int month = 0;
int day = 0;
int hour = 0;
int minute = 0;
int second = 0;
diminuto_ticks_t ticks = 0;
do {
length = strlen(*tempp);
if (!((sizeof(SUFFIX) < length) && (length < sizeof(diminuto_path_t)))) {
errno = ENAMETOOLONG;
diminuto_perror("diminuto_observation_checkpoint: strlen");
break;
}
length += 1; /* Include trailing NUL. */
path = (char *)alloca(length - sizeof(SUFFIX) + sizeof(TIMESTAMP)); /* No error return. */
strncpy(path, *tempp, length - sizeof(SUFFIX));
now = diminuto_time_clock();
if (now < 0) {
break;
}
rc = diminuto_time_zulu(now, &year, &month, &day, &hour, &minute, &second, &ticks);
if (rc < 0) {
break;
}
ticks = diminuto_frequency_ticks2units(ticks, 1000000);
snprintf(&(path[length - sizeof(SUFFIX)]), sizeof(TIMESTAMP), "-%04d%02d%02dT%02d%02d%02dZ%06lld", year, month, day, hour, minute, second, (diminuto_lld_t)ticks);
rc = fflush(fp);
if (rc != 0) {
diminuto_perror("diminuto_observation_checkpoint: fflush");
/* Fall through. */
}
rc = link(*tempp, path);
if (rc < 0) {
diminuto_perror("diminuto_observation_checkpoint: link");
break;
}
result = fp;
} while (0);
return result;
}
FILE * diminuto_observation_discard(FILE * fp, char ** tempp)
{
int rc = -1;
do {
rc = fclose(fp);
if (rc != 0) {
diminuto_perror("diminuto_observation_discard: fclose");
break;
}
/*
* If fclose(3) succeeds but unlink(2) does not, we still return the
* original FILE pointer to indicate failure, even though it is no
* longer useful. We must do the fclose(3) prior to the rename(2) to
* insure the renamed file is immediately inaccessible.
*/
rc = unlink(*tempp);
if (rc < 0) {
diminuto_perror("diminuto_observation_discard: unlink");
break;
}
free(*tempp);
*tempp = (char *)0;
fp = (FILE *)0;
} while (0);
return fp;
}