path: root/prism/util/pm_string.h

/** * @file pm_string.h * * A generic string type that can have various ownership semantics. */ #ifndef PRISM_STRING_H #define PRISM_STRING_H #include "prism/defines.h" #include <assert.h> #include <errno.h> #include <stdbool.h> #include <stddef.h> #include <stdlib.h> #include <string.h> // The following headers are necessary to read files using demand paging. #ifdef _WIN32 #include <windows.h> #elif defined(_POSIX_MAPPED_FILES) #include <fcntl.h> #include <sys/mman.h> #include <sys/stat.h> #elif defined(PRISM_HAS_FILESYSTEM) #include <fcntl.h> #include <sys/stat.h> #endif /** * A generic string type that can have various ownership semantics. */ typedef struct { /** A pointer to the start of the string. */ const uint8_t *source; /** The length of the string in bytes of memory. */ size_t length; /** The type of the string. This field determines how the string should be freed. */ enum { /** This string is a constant string, and should not be freed. */ PM_STRING_CONSTANT, /** This is a slice of another string, and should not be freed. */ PM_STRING_SHARED, /** This string owns its memory, and should be freed using `pm_string_free`. */ PM_STRING_OWNED, #ifdef PRISM_HAS_MMAP /** This string is a memory-mapped file, and should be freed using `pm_string_free`. */ PM_STRING_MAPPED #endif } type; } pm_string_t; /** * Returns the size of the pm_string_t struct. This is necessary to allocate the * correct amount of memory in the FFI backend. * * @return The size of the pm_string_t struct. */ PRISM_EXPORTED_FUNCTION size_t pm_string_sizeof(void); /** * Defines an empty string. This is useful for initializing a string that will * be filled in later. */ #define PM_STRING_EMPTY ((pm_string_t) { .type = PM_STRING_CONSTANT, .source = NULL, .length = 0 }) /** * Initialize a shared string that is based on initial input. * * @param string The string to initialize. * @param start The start of the string. * @param end The end of the string. */ void pm_string_shared_init(pm_string_t *string, const uint8_t *start, const uint8_t *end); /** * Initialize an owned string that is responsible for freeing allocated memory. * * @param string The string to initialize. * @param source The source of the string. * @param length The length of the string. */ void pm_string_owned_init(pm_string_t *string, uint8_t *source, size_t length); /** * Initialize a constant string that doesn't own its memory source. * * @param string The string to initialize. * @param source The source of the string. * @param length The length of the string. */ void pm_string_constant_init(pm_string_t *string, const char *source, size_t length); /** * Represents the result of calling pm_string_mapped_init or * pm_string_file_init. We need this additional information because there is * not a platform-agnostic way to indicate that the file that was attempted to * be opened was a directory. */ typedef enum { /** Indicates that the string was successfully initialized. */ PM_STRING_INIT_SUCCESS = 0, /** * Indicates a generic error from a string_*_init function, where the type * of error should be read from `errno` or `GetLastError()`. */ PM_STRING_INIT_ERROR_GENERIC = 1, /** * Indicates that the file that was attempted to be opened was a directory. */ PM_STRING_INIT_ERROR_DIRECTORY = 2 } pm_string_init_result_t; /** * Read the file indicated by the filepath parameter into source and load its * contents and size into the given `pm_string_t`. The given `pm_string_t` * should be freed using `pm_string_free` when it is no longer used. * * We want to use demand paging as much as possible in order to avoid having to * read the entire file into memory (which could be detrimental to performance * for large files). This means that if we're on windows we'll use * `MapViewOfFile`, on POSIX systems that have access to `mmap` we'll use * `mmap`, and on other POSIX systems we'll use `read`. * * @param string The string to initialize. * @param filepath The filepath to read. * @return The success of the read, indicated by the value of the enum. */ PRISM_EXPORTED_FUNCTION pm_string_init_result_t pm_string_mapped_init(pm_string_t *string, const char *filepath); /** * Read the file indicated by the filepath parameter into source and load its * contents and size into the given `pm_string_t`. The given `pm_string_t` * should be freed using `pm_string_free` when it is no longer used. * * @param string The string to initialize. * @param filepath The filepath to read. * @return The success of the read, indicated by the value of the enum. */ PRISM_EXPORTED_FUNCTION pm_string_init_result_t pm_string_file_init(pm_string_t *string, const char *filepath); /** * Ensure the string is owned. If it is not, then reinitialize it as owned and * copy over the previous source. * * @param string The string to ensure is owned. */ void pm_string_ensure_owned(pm_string_t *string); /** * Compare the underlying lengths and bytes of two strings. Returns 0 if the * strings are equal, a negative number if the left string is less than the * right string, and a positive number if the left string is greater than the * right string. * * @param left The left string to compare. * @param right The right string to compare. * @return The comparison result. */ int pm_string_compare(const pm_string_t *left, const pm_string_t *right); /** * Returns the length associated with the string. * * @param string The string to get the length of. * @return The length of the string. */ PRISM_EXPORTED_FUNCTION size_t pm_string_length(const pm_string_t *string); /** * Returns the start pointer associated with the string. * * @param string The string to get the start pointer of. * @return The start pointer of the string. */ PRISM_EXPORTED_FUNCTION const uint8_t * pm_string_source(const pm_string_t *string); /** * Free the associated memory of the given string. * * @param string The string to free. */ PRISM_EXPORTED_FUNCTION void pm_string_free(pm_string_t *string); #endif