datastore.c: Improve error handling and docs.

- Add Doxygen comments for all functions (some TODOs remain).

 - Check for invalid input parameters (such as NULL pointers etc).

 - Return SR_ERR_ARG upon invalid input parameters.

 - Make sr_datastore_put() return int instead of void, so we can pass
   an error code (SR_OK, SR_ERR_MALLOC, and so on) to the caller.
This commit is contained in:
Uwe Hermann 2011-12-25 19:59:15 +01:00
parent 7a6ec0c376
commit 15278f3e9c
2 changed files with 140 additions and 13 deletions

View File

@ -26,13 +26,40 @@
static gpointer new_chunk(struct sr_datastore **ds);
/**
* Create a new datastore with the specified unit size.
*
* The unit size is fixed once the datastore is created, and cannot be
* changed later on, neither can data be added to the datastore with
* different unit sizes later.
*
* It is the caller's responsibility to free the allocated memory of the
* datastore via the sr_datastore_destroy() function, if no longer needed.
*
* TODO: Unitsize should probably be unsigned int or uint32_t or similar.
* TODO: This function should have a 'chunksize' parameter, and
* struct sr_datastore a 'chunksize' field.
*
* @param unitsize The unit size (>= 1) to be used for this datastore.
* @param ds Pointer to a variable which will hold the newly created
* datastore structure.
*
* @return SR_OK upon success, SR_ERR_MALLOC upon memory allocation errors,
* or SR_ERR_ARG upon invalid arguments. If something other than SR_OK
* is returned, the value of 'ds' is undefined.
*/
int sr_datastore_new(int unitsize, struct sr_datastore **ds)
{
if (!ds)
return SR_ERR;
if (!ds) {
sr_err("ds: %s: ds was NULL", __func__);
return SR_ERR_ARG;
}
if (unitsize <= 0)
return SR_ERR; /* TODO: Different error? */
if (unitsize <= 0) {
sr_err("ds: %s: unitsize was %d, but it must be >= 1",
__func__, unitsize);
return SR_ERR_ARG;
}
if (!(*ds = g_try_malloc(sizeof(struct sr_datastore)))) {
sr_err("ds: %s: ds malloc failed", __func__);
@ -46,23 +73,64 @@ int sr_datastore_new(int unitsize, struct sr_datastore **ds)
return SR_OK;
}
/**
* Destroy the specified datastore and free the memory used by it.
*
* This will free the memory used by the data in the datastore's 'chunklist',
* by the chunklist data structure itself, and by the datastore struct.
*
* @param ds The datastore to destroy.
*
* @return SR_OK upon success, SR_ERR_ARG upon invalid arguments.
*/
int sr_datastore_destroy(struct sr_datastore *ds)
{
GSList *chunk;
if (!ds)
return SR_ERR;
if (!ds) {
sr_err("ds: %s: ds was NULL", __func__);
return SR_ERR_ARG;
}
for (chunk = ds->chunklist; chunk; chunk = chunk->next)
g_free(chunk->data);
g_slist_free(ds->chunklist);
g_free(ds);
/* TODO: Set ds = NULL? */
return SR_OK;
}
void sr_datastore_put(struct sr_datastore *ds, void *data, unsigned int length,
int in_unitsize, int *probelist)
/**
* Append some data to the specified datastore.
*
* TODO: More elaborate function description.
*
* TODO: This function should use the (not yet available) 'chunksize' field
* of struct sr_datastore (instead of hardcoding DATASTORE_CHUNKSIZE).
* TODO: in_unitsize and probelist are unused?
* TODO: A few of the parameters can be const.
* TODO: Handle new_chunk() returning NULL.
* TODO: Ideally, 'ds' should be unmodified upon errors.
*
* @param ds Pointer to the datastore which shall receive the data.
* Must not be NULL.
* @param data Pointer to the memory buffer containing the data to add.
* Must not be NULL. TODO: Data format?
* @param length Length of the data to add (in number of bytes).
* TODO: Should 0 be allowed as length?
* @param in_unitsize The unit size (>= 1) of the input data.
* @param probelist Pointer to a list of integers (probe numbers). The probe
* numbers in this list are 1-based, i.e. the first probe
* is expected to be numbered 1 (not 0!). Must not be NULL.
*
* @return SR_OK upon success, SR_ERR_MALLOC upon memory allocation errors,
* or SR_ERR_ARG upon invalid arguments. If something other than SR_OK
* is returned, the value/state of 'ds' is undefined.
*/
int sr_datastore_put(struct sr_datastore *ds, void *data, unsigned int length,
int in_unitsize, int *probelist)
{
unsigned int stored;
int capacity, size, num_chunks, chunk_bytes_free, chunk_offset;
@ -72,18 +140,49 @@ void sr_datastore_put(struct sr_datastore *ds, void *data, unsigned int length,
(void)in_unitsize;
(void)probelist;
if (!ds) {
sr_err("ds: %s: ds was NULL", __func__);
return SR_ERR_ARG;
}
/* Unitsize must not be 0, we'll divide by 0 otherwise. */
if (ds->ds_unitsize == 0) {
sr_err("ds: %s: ds->ds_unitsize was 0", __func__);
return SR_ERR_ARG;
}
if (!data) {
sr_err("ds: %s: data was NULL", __func__);
return SR_ERR_ARG;
}
if (in_unitsize < 1) {
sr_err("ds: %s: in_unitsize was %d, but it must be >= 1",
__func__, in_unitsize);
return SR_ERR_ARG;
}
if (!probelist) {
sr_err("ds: %s: probelist was NULL", __func__);
return SR_ERR_ARG;
}
/* Get the last chunk in the list, or create a new one if needed. */
if (ds->chunklist == NULL)
chunk = new_chunk(&ds);
else
chunk = g_slist_last(ds->chunklist)->data;
/* Get/calculate number of chunks, free space, etc. */
num_chunks = g_slist_length(ds->chunklist);
capacity = (num_chunks * DATASTORE_CHUNKSIZE);
chunk_bytes_free = capacity - (ds->ds_unitsize * ds->num_units);
chunk_offset = capacity - (DATASTORE_CHUNKSIZE * (num_chunks - 1))
- chunk_bytes_free;
stored = 0;
while (stored < length) {
/* No more free space left, allocate a new chunk. */
if (chunk_bytes_free == 0) {
chunk = new_chunk(&ds);
chunk_bytes_free = DATASTORE_CHUNKSIZE;
@ -100,17 +199,45 @@ void sr_datastore_put(struct sr_datastore *ds, void *data, unsigned int length,
chunk_bytes_free -= size;
stored += size;
}
ds->num_units += stored / ds->ds_unitsize;
return SR_OK;
}
/**
* Allocate a new memory chunk, append it to the datastore's chunklist.
*
* The newly allocated chunk is added to the datastore's chunklist by this
* function, and the return value additionally points to the new chunk.
*
* The allocated memory is guaranteed to be cleared.
*
* TODO: This function should use the datastore's 'chunksize' field instead
* of hardcoding DATASTORE_CHUNKSIZE.
* TODO: Return int, so we can return SR_OK / SR_ERR_ARG / SR_ERR_MALLOC?
*
* @param ds Pointer to a variable which holds the datastore structure.
* Must not be NULL. The contents of 'ds' are modified in-place.
*
* @return Pointer to the newly allocated chunk, or NULL upon failure.
*/
static gpointer new_chunk(struct sr_datastore **ds)
{
gpointer chunk;
if (!(chunk = malloc(DATASTORE_CHUNKSIZE * (*ds)->ds_unitsize)))
return NULL;
if (!ds) {
sr_err("ds: %s: ds was NULL", __func__);
return NULL; /* TODO: SR_ERR_ARG later? */
}
chunk = g_try_malloc0(DATASTORE_CHUNKSIZE * (*ds)->ds_unitsize);
if (!chunk) {
sr_err("ds: %s: chunk malloc failed", __func__);
return NULL; /* TODO: SR_ERR_MALLOC later? */
}
(*ds)->chunklist = g_slist_append((*ds)->chunklist, chunk);
return chunk;
return chunk; /* TODO: SR_OK later? */
}

View File

@ -34,8 +34,8 @@ int sr_get_loglevel(void);
int sr_datastore_new(int unitsize, struct sr_datastore **ds);
int sr_datastore_destroy(struct sr_datastore *ds);
void sr_datastore_put(struct sr_datastore *ds, void *data, unsigned int length,
int in_unitsize, int *probelist);
int sr_datastore_put(struct sr_datastore *ds, void *data, unsigned int length,
int in_unitsize, int *probelist);
/*--- device.c --------------------------------------------------------------*/