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GLib Reference Manual | ![]() |
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#include <glib.h> enum GChecksumType; gssize g_checksum_type_get_length (GChecksumType checksum_type); GChecksum; GChecksum* g_checksum_new (GChecksumType checksum_type); GChecksum* g_checksum_copy (const GChecksum *checksum); void g_checksum_free (GChecksum *checksum); void g_checksum_update (GChecksum *checksum, const guchar *data, gssize length); const gchar* g_checksum_get_string (GChecksum *checksum); void g_checksum_get_digest (GChecksum *checksum, guint8 *buffer, gsize *digest_len); gchar* g_compute_checksum_for_data (GChecksumType checksum_type, const guchar *data, gsize length); gchar* g_compute_checksum_for_string (GChecksumType checksum_type, const gchar *str, gssize length);
GLib provides a generic API for computing checksums (or "digests") for a sequence of arbitrary bytes, using various hashing algorithms like MD5, SHA-1 and SHA-256. Checksums are commonly used in various environments and specifications.
GLib supports incremental checksums using the GChecksum data structure, by calling g_checksum_update() as long as there's data available and then using g_checksum_get_string() or g_checksum_get_digest() to compute the checksum and return it either as a string in hexadecimal form, or as a raw sequence of bytes. To compute the checksum for binary blobs and NUL-terminated strings in one go, use the convenience functions g_compute_checksum_for_data() and g_compute_checksum_for_string(), respectively.
Support for checksums has been added in GLib 2.16
typedef enum { G_CHECKSUM_MD5, G_CHECKSUM_SHA1, G_CHECKSUM_SHA256 } GChecksumType;
The hashing algorithm to be used by GChecksum when performing the digest of some data.
Note that the GChecksumType enumeration may be extended at a later date to include new hashing algorithm types.
G_CHECKSUM_MD5 | Use the MD5 hashing algorithm |
G_CHECKSUM_SHA1 | Use the SHA-1 hashing algorithm |
G_CHECKSUM_SHA256 | Use the SHA-256 hashing algorithm |
Since 2.16
gssize g_checksum_type_get_length (GChecksumType checksum_type);
Gets the length in bytes of digests of type checksum_type
checksum_type : | a GChecksumType |
Returns : | the checksum length, or -1 if checksum_type is not supported. |
Since 2.16
GChecksum* g_checksum_new (GChecksumType checksum_type);
Creates a new GChecksum, using the checksum algorithm checksum_type. If the checksum_type is not known, NULL is returned. A GChecksum can be used to compute the checksum, or digest, of an arbitrary binary blob, using different hashing algorithms.
A GChecksum works by feeding a binary blob through g_checksum_update() until there is data to be checked; the digest can then be extracted using g_checksum_get_string(), which will return the checksum as a hexadecimal string; or g_checksum_get_digest(), which will return a vector of raw bytes. Once either g_checksum_get_string() or g_checksum_get_digest() have been called on a GChecksum, the checksum will be closed and it won't be possible to call g_checksum_update() on it anymore.
checksum_type : | the desired type of checksum |
Returns : | the newly created GChecksum, or NULL. Use g_checksum_free() to free the memory allocated by it. |
Since 2.16
GChecksum* g_checksum_copy (const GChecksum *checksum);
Copies a GChecksum. If checksum has been closed, by calling g_checksum_get_string() or g_checksum_get_digest(), the copied checksum will be closed as well.
checksum : | the GChecksum to copy |
Returns : | the copy of the passed GChecksum. Use g_checksum_free() when finished using it. |
Since 2.16
void g_checksum_free (GChecksum *checksum);
Frees the memory allocated for checksum.
checksum : | a GChecksum |
Since 2.16
void g_checksum_update (GChecksum *checksum, const guchar *data, gssize length);
Feeds data into an existing GChecksum. The checksum must still be open, that is g_checksum_get_string() or g_checksum_get_digest() must not have been called on checksum.
checksum : | a GChecksum |
data : | buffer used to compute the checksum |
length : | size of the buffer, or -1 if it is a null-terminated string. |
Since 2.16
const gchar* g_checksum_get_string (GChecksum *checksum);
Gets the digest as an hexadecimal string.
Once this function has been called the GChecksum can no longer be updated with g_checksum_update().
checksum : | a GChecksum |
Returns : | the hexadecimal representation of the checksum. The returned string is owned by the checksum and should not be modified or freed. |
Since 2.16
void g_checksum_get_digest (GChecksum *checksum, guint8 *buffer, gsize *digest_len);
Gets the digest from checksum as a raw binary vector and places it into buffer. The size of the digest depends on the type of checksum.
Once this function has been called, the GChecksum is closed and can no longer be updated with g_checksum_update().
checksum : | a GChecksum |
buffer : | output buffer |
digest_len : | an inout parameter. The caller initializes it to the size of buffer. After the call it contains the length of the digest. |
Since 2.16
gchar* g_compute_checksum_for_data (GChecksumType checksum_type, const guchar *data, gsize length);
Computes the checksum for a binary data of length. This is a convenience wrapper for g_checksum_new(), g_checksum_get_string() and g_checksum_free().
checksum_type : | a GChecksumType |
data : | binary blob to compute the digest of |
length : | length of data |
Returns : | the digest of the binary data as a string in hexadecimal. The returned string should be freed with g_free() when done using it. |
Since 2.16
gchar* g_compute_checksum_for_string (GChecksumType checksum_type, const gchar *str, gssize length);
Computes the checksum of a string.
checksum_type : | a GChecksumType |
str : | the string to compute the checksum of |
length : | the length of the string, or -1 if the string is null-terminated. |
Returns : | the checksum as a hexadecimal string. The returned string should be freed with g_free() when done using it. |
Since 2.16