path: root/src/shared.c

/**
 * @file shared.c
 * @author syxhe (https://t.me/syxhe)
 * @brief A collection of functions and macros shared between files, or without a better place
 * @version 0.1
 * @date 2025-06-09
 *
 * @copyright Copyright (c) 2025
 *
 */

#ifndef __VXGG_REWRITE___SHARED_C___3880294315821___
#define __VXGG_REWRITE___SHARED_C___3880294315821___ 1

#define STATIC_ARRAY_LEN(arr) (sizeof((arr))/sizeof((arr)[0]))

#define ERRRET(errval, retval) do {\
    errno = (errval);\
    return (retval);\
} while (0)

/// Determines how `vx__alloc()` functions exit. `> 0` calls `error()`, otherwise calls `abort()`. `vx__alloc()` type functions will
/// always halt execution
#define ___VXGG___VXALLOC_EXIT_ON_ERROR___ 1

/// Determines whether vxgg functions that can error print out a short warning of the error when one is encountered.
/// `> 0` will print diagnostic error messages, and will do nothing otherwise
#define ___VXGG___VERBOSE_ERRORS___ 1

//! Macro to exit on an alloc error instead of doing the terrible nested if statement that was being used previously
#define XALLOC_EXIT(msg, ...) do {\
    if(!___VXGG___VXALLOC_EXIT_ON_ERROR___)\
        abort();\
    if(!___VXGG___VERBOSE_ERRORS___)\
        exit(EXIT_FAILURE);\
    error(EXIT_FAILURE, errno, (msg)__VA_ARGS__);\
    exit(EXIT_FAILURE); /* Makes gcc happy */\
} while (0)

//! Error macro that gcc will not complain about
#define ERROR(status, errnum, format, ...) do {error((status), (errnum), (format)__VA_ARGS__); exit((status));} while (0)
//! Spit out a warning using `error`
#define WARN(errnum, format, ...) do {error(0, (errnum), (format)__VA_ARGS__);} while (0)


typedef int (*gcallback)(void*);    //!< Generic callback signature
typedef void (*fcallback)(void*);   //!< free()-like callback signature

/**
 * @brief A locally defined structure designed for easier function cleanup
 *
 */
typedef struct cl {
    fcallback *callbacks;   //!< An array of free()-like callbacks. Actual Type: fcallback callbacks[]
    void * *arguments;      //!< An array of void pointers. Actual Type: void *arguments[]
    int size;               //!< The size of each array
    int used;               //!< The current number of used elements in each array
} cleanup;
// While the cleanup thing is useful, it's also a complete fucking mess. Swtich to error gotos asap

#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <error.h>

#include <threads.h>

/**
 * @brief Read the entire contents of a file descriptor into a malloc()'ed buffer
 *
 * @param str Pointer to a string. Will be replaced with the malloc()'ed string
 * @param initsize The initial size of the malloc()'ed string
 * @param fd A file descriptor to read from
 * @retval (int)[-1, strlen(str)] Returns the size of the array on success, or -1 on error
 * @note The allocated buffer will expand and contract as necessary, but it's recommended to set `initsize` to some value close to or equal to the size of the file being read to reduce the number of resizes
 */
int rwbuf(char **str, unsigned long int initsize, int fd) {
	// Try to read bytes from fd into str
		// Bytes read == 0, return 0
		// Bytes read < 0, free string, return -1;
	// When string hits capacity, double the capacity, and reallocate the string

	if(!str || initsize < 1 || fd < 0) ERRRET(EINVAL, -1);

    char *lstr = NULL, *tmp = NULL;
	ssize_t bytesread = -1;
	int csize = initsize, ccap = initsize, eflag = 0;

	lstr = calloc(initsize, sizeof(char));
	if(!lstr) return -1;

	while((bytesread = read(fd, lstr + (csize - ccap), ccap)) > 0) {
		ccap -= bytesread;
		if(ccap <= 0) {
			csize *= 2;
			ccap = csize / 2;

			tmp = realloc(lstr, csize * sizeof(char));
			if(!tmp) {eflag = 1; goto ERR_rwbuf;}
			lstr = tmp;
		}
	}
	if(bytesread < 0) {eflag = 2; goto ERR_rwbuf;}

	if(lstr) {
		tmp = realloc(lstr, csize - ccap + 1);
		if(!tmp) {eflag = 3; goto ERR_rwbuf;}
		lstr = tmp;
	}

    if(lstr && fd == STDIN_FILENO) {
        lstr[csize - ccap - 1] = '\0'; // Don't include the newline
    }

	*str = lstr;
	return csize - ccap;

ERR_rwbuf:
    if(___VXGG___VERBOSE_ERRORS___) {
        switch (eflag) {
            case 1: WARN(errno, "Could not reallocate enough space for lstr",);
            case 2: WARN(errno, "Ran into a read() error",);
            case 3: WARN(errno, "Could not shrink lstr after reading buffer",);
            default: WARN(errno, "Ran into some error",);
        }
    }
    free(lstr);

    return -1;
}


/**
 * @brief Write the entire contents of a buffer into a file descriptor
 *
 * @param fd The file descriptor to write to
 * @param buf The buffer to write from
 * @param len The length of the buffer
 * @retval (int)[-1, 0] Returns 0 on success, -1 on error
 */

int wwbuf(int fd, const unsigned char *buf, int len) {
	if(!buf || len <= 0 || fd < 0) ERRRET(EINVAL, -1);

    int total = 0;
    int left = len;
    int n = -1;

    while(total < len) {
        if((n = write(fd, buf + total, left)) < 0)
            break;

        total += n;
        left -= n;
    }

    return (n < 0) ? -1 : 0;
}
// Adapted from Beej's `sendall()` function
// https://beej.us/guide/bgnet/html/split/slightly-advanced-techniques.html#sendall
    // Thanks Beej!

/**
 * @brief `dirname()` reimplementation that returns a malloc()'ed string
 *
 * @param path The filepath to be inspected
 * @retval (char*)[NULL, char*] Returns a null-terminated string on success, or `null` on error
 */
char * vxdirname(const char * const path) {
	char *tmp = NULL;
	if(!path) { // Path being null is a special case which should return early, before anything else (as to avoid null dereference)
		tmp = strdup(".");
		if(!tmp && ___VXGG___VERBOSE_ERRORS___) WARN(errno, "<vxdirname> could not strdup \".\" for set path result \"NULL\"", );
		return tmp;
	}

    const char * const special[] = {"..", ".", "/"};
    for(int i = 0; i < STATIC_ARRAY_LEN(special); i++) {
        if(strncmp(path, special[i], strlen(special[i])) == 0) {
            tmp = strdup(special[i]);
            if(!tmp && ___VXGG___VERBOSE_ERRORS___) WARN(errno, "<vxdirname> could not strdup a set path result", );
            return tmp;
        }
    }

	/* From the manpages: (man 3 dirname)
	//		+=======================================+
	//		|	path		dirname		basename	|
	//		+=======================================+
	//		|	/usr/lib   	/usr      	lib			|
	//		|	/usr/      	/         	usr			|
	//		|	usr        	.         	usr			|
	//		+=======================================+
	*/

	// Get a temp copy of the path for manipulation purposes
	tmp = strdup(path);
	if(!tmp) {
		if(___VXGG___VERBOSE_ERRORS___) WARN(errno, "<vxdirname> could not strdup the given path \"%s\" for internal manipulation", , path);
		return NULL;
	}

	// If there's a trailing '/', delete it
	size_t pathlen = strlen(path);
	if(tmp[pathlen - 1] == '/') {
		tmp[pathlen - 1] = '\0';
		pathlen--;
	}

	// Ok, I think the easiest way to do this (if maybe a bit slow) is to count the number of '/'s in the string
		// If there's only one, return '/'
		// If there are 2 or more, find the last one in the list and set it to '\0'

	size_t count = 0;
	for(size_t i = 0; i < pathlen; i++) {
		if(tmp[i] == '/')
			count++;
	}

    if(count < 2) {
        free(tmp);
        if(count == 1) tmp = strdup("/");
        else tmp = strdup(".");

        if(!tmp && ___VXGG___VERBOSE_ERRORS___) WARN(errno, "<vxdirname> Error: Could not strdup \"%s\" for set path result", , ((count == 0) ? "." : "/"));
        return tmp;
    }

	for(size_t i = 0, c2 = 0; i < pathlen; i++) {
		if(tmp[i] == '/')
			c2++;
		if(c2 == count)
			tmp[i] = '\0';
	}

	char * const actual = strdup(tmp);
	free(tmp);
	if(!actual && ___VXGG___VERBOSE_ERRORS___) WARN(errno, "<xdirname> could not strdup tmp string to make a shorter end string", );

	return actual;
}


/**
 * @brief Initialize a cleanup object
 *
 * @param loc The cleanup object to be initialized
 * @param callbacks An array of free()-like callbacks. Must be `size` elements long
 * @param arguments An array of void pointers. Must be `size` elements long
 * @param size The number of elements the callbacks and arguments array are long
 * @retval (int)[-1, 0] Returns 0 on success, -1 on error
 */
int cleanup_init(cleanup *loc, fcallback callbacks[], void *arguments[], int size) {
    if(!loc || !callbacks || !arguments || size <= 0) ERRRET(EINVAL, -1);

    loc->callbacks = callbacks;
    loc->arguments = arguments;
    loc->size = size;
    loc->used = 0;

    return 0;
}

/**
 * @brief Register a new callback and argument onto a cleanup stack
 *
 * @param loc The cleanup object to modify
 * @param cb A free()-like callback to run
 * @param arg A piece of data for the callback to run
 * @retval (int)[-1, 0] Returns 0 on success, -1 on error
 */
int cleanup_register(cleanup *loc, fcallback cb, void *arg) {
    if(!loc || !cb) ERRRET(EINVAL, -1);
    if(loc->used >= loc->size || loc->used < 0) ERRRET(ENOMEM, -1);

    loc->callbacks[loc->used] = cb;
    loc->arguments[loc->used] = arg;
    loc->used++;

    return 0;
}

/**
 * @brief Conditionally register a callback and argument
 *
 * @param loc The cleanup object to modify
 * @param cb A free()-like callback to run
 * @param arg A piece of data for the callback to run
 * @param flag Whether or not the register should take place. Will not run if `flag` is non-zero
 * @retval (int)[-1, 0] Returns 0 on success or skip, -1 on error
 */
int cleanup_cndregister(cleanup *loc, fcallback cb, void *arg, unsigned char flag) {
    if(flag) return 0;
    return cleanup_register(loc, cb, arg);
}

/**
 * @brief Clear a cleanup object
 * @attention Does not free any registered callbacks or arguments, just marks them as available space
 *
 * @param loc The cleanup object to modify
 * @retval (int)[-1, 0] Returns 0 on success, -1 on error
 */
int cleanup_clear(cleanup *loc) {
    if(!loc) ERRRET(EINVAL, -1);
    loc->used = 0;
    return 0;
}

/**
 * @brief Fires all the registered callbacks and arguments in a cleanup object in FIFO (stack) order
 *
 * @param loc The cleanup object to fire
 * @retval (int)[-1, 0] Returns 0 on success, -1 on error
 */
int cleanup_fire(cleanup *loc) {
    if(!loc) ERRRET(EINVAL, -1);

    for(int i = (loc->used - 1); i >= 0; i--) {
        if(loc->callbacks[i] == NULL) {
            error(0, EINVAL, "cleanup_fire: refusing to run null callback...");
            continue;
        }

        loc->callbacks[i](loc->arguments[i]);
    }
    cleanup_clear(loc);

    return 0;
}

/**
 * @brief Conditionally fires a cleanup object
 *
 * @param loc The cleanup object in question
 * @param flag Whether the object should be fired. Will skip firing if non-zero
 * @retval (int)[-1, 0] Returns 0 on success, -1 on error
 */
int cleanup_cndfire(cleanup *loc, unsigned char flag) {
    if(flag)
        return cleanup_fire(loc);
    return 0;
}

/**
 * @brief Initializes a set of variables suitable for use in the cleanup macros
 * @param size The number of elements long each array should be
 */
#define cleanup_CREATE(size) \
cleanup __CLEANUP; \
fcallback __CLEANUP_FUNCS[(size)]; \
void *__CLEANUP_ARGS[(size)]; \
unsigned char __FLAG = 0; \
cleanup_init(&__CLEANUP, __CLEANUP_FUNCS, __CLEANUP_ARGS, (size))

//! Register a callback-argument pair using the local cleanup object
#define cleanup_REGISTER(cb, arg)       cleanup_register(&__CLEANUP, (cb), (arg))
//! Conditionally register a callback-argument pair using the local cleanup object
#define cleanup_CNDREGISTER(cb, arg)    cleanup_cndregister(&__CLEANUP, (cb), (arg), __FLAG)
//! Clean the local cleanup object
#define cleanup_CLEAR()                 cleanup_clear(&__CLEANUP)
//! Fire the local cleanup object
#define cleanup_FIRE()                  cleanup_fire(&__CLEANUP)
//! Conditionally fire the local cleanup object
#define cleanup_CNDFIRE()               cleanup_cndfire(&__CLEANUP, __FLAG)
//! Set the local cleanup flag to a non-zero number
#define cleanup_MARK()                  (__FLAG = 1)
//! Set the local cleanup flag to zero
#define cleanup_UNMARK()                (__FLAG = 0)
//! Check if the local cleanup flag is non-zero
#define cleanup_ERRORFLAGGED            (__FLAG != 0)
//! Conditionally execute some `code` if the local cleanup flag has not been marked
#define cleanup_CNDEXEC(code)           while(!cleanup_ERRORFLAGGED) {code; break;}
//! Conditionally fire the local cleanup object and return `ret`
#define cleanup_CNDFIRERET(ret)         do {cleanup_CNDFIRE(); return ret;} while (0)

#endif