qLibc

qcount.c
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1/******************************************************************************
2 * qLibc
3 *
4 * Copyright (c) 2010-2015 Seungyoung Kim.
5 * All rights reserved.
6 *
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8 * modification, are permitted provided that the following conditions are met:
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28
29/**
30 * @file qcount.c Counter file handling APIs.
31 */
32
33#include <stdio.h>
34#include <stdlib.h>
35#include <stdbool.h>
36#include <stdint.h>
37#include <inttypes.h>
38#include <string.h>
39#include <fcntl.h>
40#include <unistd.h>
41#include <sys/types.h>
42#include <sys/stat.h>
43#include "qinternal.h"
44#include "utilities/qstring.h"
45#include "utilities/qcount.h"
46
47/**
48 * Read counter(integer) from file with advisory file locking.
49 *
50 * @param filepath file path
51 *
52 * @return counter value readed from file. in case of failure, returns 0.
53 *
54 * @code
55 * qcount_save("number.dat", 75);
56 * int count = qcount_read("number.dat");
57 * @endcode
58 *
59 * @code
60 * ---- number.dat ----
61 * 75
62 * --------------------
63 * @endcode
64 */
65int64_t qcount_read(const char *filepath) {
66 int fd = open(filepath, O_RDONLY, 0);
67 if (fd < 0)
68 return 0;
69
70 char buf[20 + 1];
71 ssize_t readed = read(fd, buf, (sizeof(buf) - 1));
72 close(fd);
73
74 int64_t num = 0;
75 if (readed > 0) {
76 buf[readed] = '\0';
77 num = atoll(buf);
78 }
79
80 return num;
81}
82
83/**
84 * Save counter(integer) to file with advisory file locking.
85 *
86 * @param filepath file path
87 * @param number counter integer value
88 *
89 * @return true if successful, otherwise returns false.
90 *
91 * @code
92 * qcount_save("number.dat", 75);
93 * @endcode
94 */
95 bool qcount_save(const char *filepath, int64_t number) {
96 int fd = open(filepath, O_CREAT | O_WRONLY | O_TRUNC,
97 (S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH));
98 if (fd < 0)
99 return false;
100
101 char *str = qstrdupf("%"PRId64, number);
102 ssize_t updated = write(fd, str, strlen(str));
103 close(fd);
104
105 if (updated > 0)
106 return true;
107 return false;
108}
109
110/**
111 * Increases(or decrease) the counter value as much as specified number
112 * with advisory file locking.
113 *
114 * @param filepath file path
115 * @param number how much increase or decrease
116 *
117 * @return updated counter value. in case of failure, returns 0.
118 *
119 * @code
120 * int count;
121 * count = qcount_update("number.dat", -3);
122 * @endcode
123 */
124int64_t qcount_update(const char *filepath, int64_t number) {
125 int64_t counter = qcount_read(filepath);
126 counter += number;
127 if (qcount_save(filepath, counter) == true) {
128 return counter;
129 }
130 return 0;
131}
qcount_save
bool qcount_save(const char *filepath, int64_t number)
Save counter(integer) to file with advisory file locking.
Definition qcount.c:95
qcount_read
int64_t qcount_read(const char *filepath)
Read counter(integer) from file with advisory file locking.
Definition qcount.c:65
qcount_update
int64_t qcount_update(const char *filepath, int64_t number)
Increases(or decrease) the counter value as much as specified number with advisory file locking.
Definition qcount.c:124
qstrdupf
char * qstrdupf(const char *format,...)
Duplicate a formatted string.
Definition qstring.c:363