Add functions to load/set leap second table

src/libiso8601/000_TopSource.c

@@ -10,9 +10,12 @@
 /* Below are all the includes used throughout the library. */
 #include <ctype.h>
 #include <errno.h>
+#include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <unistd.h>
+#include <sys/stat.h>
 #include <sys/time.h>
 
 /* Useful define to alleviate typos */

src/libiso8601/100_leap.c

@@ -73,6 +73,80 @@ int iso8601_leap_elapsed(const struct iso8601_date* start, const struct iso8601_
 
 
 
+void iso8601_leap_table_set(int* new_table, int new_size)
+{
+    leap_second_days = new_table;
+    leap_second_days_num = new_size;
+}
+
+
+
+static const char* leap_table_signature = "/O9PdPZI";
+
+
+
+int iso8601_leap_table_load(const char* fname)
+{
+    struct stat st;
+    int fd, saved_errno, i, new_size, * days = 0;
+    char buf[12];
+
+    if(stat(fname, &st)) return -1;
+    if(st.st_size < 12) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    fd = open(fname, O_RDONLY);
+    if(fd == -1) return -1;
+
+    if(TEMP_FAILURE_RETRY( read(fd, buf, 12) ) != 12) goto outerr;
+    if(memcmp(buf, leap_table_signature, 8)) {
+        errno = EINVAL;
+        return -1;
+    }
+
+#define GET_UINT32(_from) ( \
+    ( ((uint8_t*)_from)[0] << 24 ) | \
+    ( ((uint8_t*)_from)[1] << 16 ) | \
+    ( ((uint8_t*)_from)[2] << 8 ) | \
+    ( ((uint8_t*)_from)[3] ) \
+)
+
+    new_size = GET_UINT32(buf + 8);
+    if((12 + new_size * 4) != st.st_size) {
+        errno = EINVAL;
+        goto outerr;
+    }
+
+    days = malloc(sizeof(int) * new_size);
+    if(!days) goto outerr;
+
+    for(i = 0; i < new_size; ++i) {
+        if(TEMP_FAILURE_RETRY( read(fd, buf, 4) ) != 4) goto outerr;
+        days[i] = GET_UINT32(buf);
+        if(i && days[i] <= days[i - 1]) {
+            errno = EINVAL;
+            goto outerr;
+        }
+    }
+
+    TEMP_FAILURE_RETRY( close(fd) );
+    iso8601_leap_table_set(days, new_size);
+    return 0;
+
+#undef GET_UINT32
+
+  outerr:
+    saved_errno = errno;
+    free(days);
+    TEMP_FAILURE_RETRY( close(fd) );
+    errno = saved_errno;
+    return -1;
+}
+
+
+
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