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qFile.c File Reference

File Handling API. More…

Defines
#define	MAX_EXTENSION_LENGTH   (5)
#define	MAX_FILESEND_CHUNK_SIZE   (32 * 1024)
Functions
bool	qFileLock (int fd)
	Lock file.
bool	qFileUnlock (int fd)
	Unlock file which is locked by qFileLock().
bool	qFileExist (const char *filepath)
	Check file existence.
char *	qFileGetName (const char *filepath)
	Get filename from filepath.
char *	qFileGetDir (const char *filepath)
	Get directory suffix from filepath.
char *	qFileGetExt (const char *filepath)
	Get extension from filepath.
off_t	qFileGetSize (const char *filepath)
	Get file size.
ssize_t	qFileSend (int outfd, int infd, size_t nbytes)
	Transfer data between file descriptors.
void *	qFileLoad (const char *filepath, size_t *nbytes)
	Load file into memory.
void *	qFileRead (FILE *fp, size_t *nbytes)
	Load file stream which has unknown size into memory.
char *	qFileReadLine (FILE *fp)
	Read string.
ssize_t	qFileSave (const char *filepath, const void *buf, size_t size, bool append)
	Save to file.

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Detailed Description

File Handling API.

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Function Documentation

bool qFileLock

(

int

fd

)

Lock file.

Parameters:

fd

file descriptor

Returns:

true if successful, otherwise returns false.

   // for file descriptor
   int fd = open(...);
   if(qFileLock(fd) == true) {
     (...atomic file access...)
     qFileUnlock(fd);
   }
   // for FILE stream object
   FILE *fp = fopen(...);
   int fd = fileno(fp);
   if(qFileLock(fd) == true) {
     (...atomic file access...)
     qFileUnlock(fd);
   }

bool qFileUnlock

(

int

fd

)

Unlock file which is locked by qFileLock().

Parameters:

fd

file descriptor

Returns:

true if successful, otherwise returns false.

bool qFileExist

(

const char *

filepath

)

Check file existence.

Parameters:

filepath

file or directory path

Returns:

true if exists, otherwise returns false;

char* qFileGetName

(

const char *

filepath

)

Get filename from filepath.

Parameters:

filepath

file or directory path

Returns:

malloced filename string

char* qFileGetDir

(

const char *

filepath

)

Get directory suffix from filepath.

Parameters:

filepath

file or directory path

Returns:

malloced filepath string

char* qFileGetExt

(

const char *

filepath

)

Get extension from filepath.

Parameters:

filepath

file or directory path

Returns:

malloced extension string which is converted to lower case.

off_t qFileGetSize

(

const char *

filepath

)

Get file size.

Parameters:

filepath

file or directory path

Returns:

the file size if exists, otherwise returns -1.

ssize_t qFileSend	(	int	outfd,
		int	infd,
		size_t	nbytes
	)

Transfer data between file descriptors.

Parameters:

	outfd	output file descriptor
	infd	input file descriptor
	size	the number of bytes to copy between file descriptors. 0 means transfer until end of infd.

Returns:

the number of bytes written to outfd.

void* qFileLoad	(	const char *	filepath,
		size_t *	nbytes
	)

Load file into memory.

Parameters:

	filepath	file path
	nbytes	has two purpost, one is to set how many bytes are readed. the other is actual the number loaded bytes will be stored. nbytes must be point 0 or NULL to read entire file.

Returns:

allocated memory pointer if successful, otherwise returns NULL.

   // loading text file
   char *text = (char *)qFileLoad("/tmp/text.txt", NULL);
   // loading binary file
   int binlen = 0;
   char *bin = (char *)qFileLoad("/tmp/binary.bin", &binlen);
   // loading partial
   int binlen = 10;
   char *bin = (char *)qFileLoad("/tmp/binary.bin", &binlen);

Note:

This method actually allocates memory more than 1 bytes than filesize then append ” character at the end. For example, when the file size is 10 bytes long, 10+1 bytes will allocated and the last byte is always ” character. So you can load text file and use without appending ” character. By the way, *size still will be returned the actual file size of 10.

void* qFileRead	(	FILE *	fp,
		size_t *	nbytes
	)

Load file stream which has unknown size into memory.

Parameters:

	fp	FILE pointer
	nbytes	has two purpost, one is to set how many bytes are readed. the other is actual the number loaded bytes will be stored. nbytes must be point 0 or NULL to read end of stream.

Returns:

allocated memory pointer if successful, otherwise returns NULL.

Note:

This method append ” character at the end of stream. but nbytes only counts actual readed bytes.

char* qFileReadLine

(

FILE *

fp

)

Read string.

Same as fgets but can be used for unlimited string line.

Parameters:

fp

FILE pointer

Returns:

allocated memory pointer if successful, otherwise returns NULL.

ssize_t qFileSave	(	const char *	filepath,
		const void *	buf,
		size_t	size,
		bool	append
	)

Save to file.

Parameters:

	filepath	file path
	buf	data
	size	the number of bytes to save
	append	false for new(if exists truncate), true for appending

Returns:

the number of bytes written if successful, otherwise returns -1.

   // save text
   char *text = "hello";
   qFileSave("/tmp/text.txt", (void*)text, strlen(text), false);
   // save binary
   int integer1 = 75;
   qFileSave("/tmp/integer.bin, (void*)&integer, sizeof(int));

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