added Cache_create

src/cache.c

@@ -92,6 +92,28 @@ int Cache_exist(const char *fn)
     return 1;
 }
 
+Cache *Cache_create(const char *fn, long len, long time)
+{
+    Cache *cf = Cache_alloc();
+
+    cf->filename = strndup(fn, MAX_PATH_LEN);
+    cf->len = len;
+    cf->time = time;
+
+    if (Data_create(cf)) {
+        Cache_free(cf);
+        fprintf(stderr, "Cache_create(): Data_create() failed!\n");
+        return NULL;
+    }
+
+    if (Meta_create(cf)) {
+        Cache_free(cf);
+        fprintf(stderr, "Cache_create(): Meta_create() failed!\n");
+        return NULL;
+    }
+    return cf;
+}
+
 Cache *Cache_open(const char *fn)
 {
     /* Create the cache in-memory data structure */
@@ -112,6 +134,11 @@ Cache *Cache_open(const char *fn)
     return cf;
 }
 
+int Meta_create(const Cache *cf)
+{
+    return Meta_write(cf);
+}
+
 int Meta_read(Cache *cf)
 {
     FILE *fp;
@@ -119,6 +146,7 @@ int Meta_read(Cache *cf)
     fp = fopen(metafn, "r");
     free(metafn);
     int res = 0;
+    int nmemb = 0;
 
     if (!fp) {
         /* The metadata file does not exist */
@@ -130,16 +158,17 @@ int Meta_read(Cache *cf)
     fread(&(cf->time), sizeof(long), 1, fp);
     fread(&(cf->nseg), sizeof(int), 1, fp);
 
-    /* Allocate some memory for the segment */
-    cf->seg = malloc(cf->nseg * sizeof(Seg));
-    if (!(cf->seg)) {
-        fprintf(stderr, "Meta_read(): malloc failure!\n");
-        exit(EXIT_FAILURE);
+    if (cf->nseg) {
+        /* Allocate some memory for the segment */
+        cf->seg = malloc(cf->nseg * sizeof(Seg));
+        if (!(cf->seg)) {
+            fprintf(stderr, "Meta_read(): malloc failure!\n");
+            exit(EXIT_FAILURE);
+        }
+        /* Read all the segment */
+        nmemb = fread(cf->seg, sizeof(Seg), cf->nseg, fp);
     }
 
-    /* Read all the segment */
-    int nmemb = fread(cf->seg, sizeof(Seg), cf->nseg, fp);
-
     /* Error checking for fread */
     if (ferror(fp)) {
         fprintf(stderr,
@@ -180,7 +209,9 @@ int Meta_write(const Cache *cf)
     fwrite(&(cf->nseg), sizeof(int), 1, fp);
 
     /* Finally write segments to the file */
-    fwrite(cf->seg, sizeof(Seg), cf->nseg, fp);
+    if (cf->nseg) {
+        fwrite(cf->seg, sizeof(Seg), cf->nseg, fp);
+    }
 
     /* Error checking for fwrite */
     if (ferror(fp)) {
@@ -206,15 +237,15 @@ int Data_create(Cache *cf)
     free(datafn);
     if (fd == -1) {
         fprintf(stderr, "Data_create(): open(): %s\n", strerror(errno));
-        return 0;
+        return -1;
     }
     if (ftruncate(fd, cf->len) == -1) {
         fprintf(stderr, "Data_create(): ftruncate(): %s\n", strerror(errno));
     }
-    if (close(fd) == -1) {
+    if (close(fd)) {
         fprintf(stderr, "Data_create(): close:(): %s\n", strerror(errno));
     }
-    return 1;
+    return 0;
 }
 
 long Data_size(const char *fn)

src/cache.h

@@ -47,11 +47,6 @@ typedef struct {
 
 /***************************** To be completed ******************************/
 
-/**
- * \brief create a cache file set
- */
-Cache *Cache_create(const char *fn, long len, long time);
-
 /**
  * \brief Read from a cache file set
  * \details This function performs the following two things:
@@ -104,12 +99,22 @@ void Cache_free(Cache *cf);
  */
 int Cache_exist(const char *fn);
 
+/**
+ * \brief create a cache file set
+ */
+Cache *Cache_create(const char *fn, long len, long time);
+
 /**
  * \brief open a cache file set
  * \warning We assume that the metadata file and the data file both exist
  */
 Cache *Cache_open(const char *fn);
 
+/**
+ * \brief create a metadata file
+ */
+int Meta_create(const Cache *cf);
+
 /**
  * \brief write a metadata file
  * \return
@@ -130,9 +135,9 @@ int Meta_read(Cache *cf);
  * \brief create a data file
  * \details We use sparse creation here
  * \return
- *  - 1 on successful creation of the data file, note that the result of
+ *  - 0 on successful creation of the data file, note that the result of
  * the ftruncate() is ignored.
- *  - 0 on failure to create the data file.
+ *  - -1 on failure to create the data file.
  */
 int Data_create(Cache *cf);