lib: add xbps_fmt_* formatted printing functions

include/xbps.h.in

@@ -2365,6 +2365,178 @@ xbps_plist_dictionary_from_file(const char *path);
 
 /**@}*/
 
+/** @addtogroup format */
+/**@{*/
+
+/**
+ * @struct xbps_fmt xbps.h "xbps.h"
+ * @brief Structure of parsed format string.
+ */
+struct xbps_fmt;
+
+/**
+ * @struct xbps_fmt xbps.h "xbps.h"
+ * @brief Structure of parsed format specifier.
+ */
+struct xbps_fmt_spec {
+	/**
+	 * @var fill
+	 * @brief Character to pad the output with.
+	 */
+	char fill;
+	/**
+	 * @var align
+	 * @brief Alignment modifier, can be `<`, `>` or `=`.
+	 *
+	 * Possible values are:
+	 * - `<`: left align.
+	 * - `>`: right align.
+	 * - `=`: place padding after the sign.
+	 */
+	char align;
+	/**
+	 * @var sign
+	 * @brief Sign modifier can be `+`, `-` or a space.
+	 *
+	 * Possible values are:
+	 * - `-`: sign negative numbers.
+	 * - `+`: sign both negative and positive numbers.
+	 * - space: sign negative numbers and add space before positive numbers.
+	 */
+	char sign;
+	/**
+	 * @var width
+	 * @brief Alignment width to pad the output to.
+	 */
+	unsigned int width;
+	/**
+	 * @var prec
+	 * @brief Precision of the output, usually for numbers.
+	 */
+	unsigned int prec;
+	/**
+	 * @var type
+	 * @brief Type specifier usually to change the output format type.
+	 *
+	 * Can contain any character, xbps_fmt_number() uses the following:
+	 * - `u`: Unsigned decimal.
+	 * - `d`: Decimal.
+	 * - `x`: Hex with lowercase letters.
+	 * - `X`: hex with uppercase letters.
+	 * - `h`: Human readable using humanize_number(3).
+	 */
+	char type;
+};
+
+/**
+ * @brief Format callback, called for each variable in the format string.
+ *
+ * A callback function should write data associated with \a var to \a fp and use
+ * \a w as alignment specifier.
+ *
+ * @param[in] fp The file to print to.
+ * @param[in] spec The format specifier.
+ * @param[in] var The format string variable name.
+ * @param[in] data Userdata passed to the xbps_fmt() function.
+ */
+typedef int (xbps_fmt_cb)(FILE *fp, const struct xbps_fmt_spec *spec, const char *var, void *data);
+
+/**
+ * @brief Parses the format string \a format.
+ *
+ * @param[in] format The format string.
+ *
+ * @return The parsed format structure, or NULL on error.
+ * The returned buffer must be freed with xbps_fmt_free().
+ * @retval EINVAL Invalid format string.
+ * @retval ERANGE Invalid alignment specifier.
+ * @retval ENOMEM Memory allocation failure.
+ */
+struct xbps_fmt *xbps_fmt_parse(const char *format);
+
+/**
+ * @brief Releases memory associated with \a fmt.
+ *
+ * @param[in] fmt The format string.
+ */
+void xbps_fmt_free(struct xbps_fmt *fmt);
+
+/**
+ * @brief Print formatted text to \a fp.
+ *
+ * @param[in] fmt Format returned by struct xbps_fmt_parse().
+ * @param[in] cb Callback function called for each variable in the format.
+ * @param[in] data Userdata passed to the callback \a cb.
+ * @param[in] fp File to print to.
+ *
+ * @return 0 on success or a negative errno.
+ * @retval 0 Success
+ */
+int xbps_fmt(const struct xbps_fmt *fmt, xbps_fmt_cb *cb, void *data, FILE *fp);
+
+/**
+ * @brief Print formatted dictionary values to \a fp.
+ *
+ * Prints formatted dictionary values as specified by the parsed \a fmt
+ * format string to \a fp.
+ *
+ * @param[in] fmt Format returned by struct xbps_fmt_parse().
+ * @param[in] dict Dictionary to print values from.
+ * @param[in] fp File to print to.
+ *
+ * @return 0 on success or value returned by \a cb.
+ * @retval 0 Success
+ */
+int xbps_fmt_dictionary(const struct xbps_fmt *fmt, xbps_dictionary_t dict, FILE *fp);
+
+/**
+ * @brief Print formatted dictionary to \a fp.
+ *
+ * Print the formatted dictionary according to the \a format format string
+ * to \a fp.
+ *
+ * @param[in] format Format string.
+ * @param[in] cb Callback function called for each variable in the format.
+ * @param[in] data Userdata passed to the callback \a cb.
+ * @param[in] fp File to print to.
+ *
+ * @return 0 on success.
+ * @retval 0 Success.
+ * @retval -EINVAL Invalid format string.
+ * @retval -ERANGE Invalid alignment specifier.
+ * @retval -ENOMEM Memory allocation failure.
+ */
+int xbps_fmts(const char *format, xbps_fmt_cb *cb, void *data, FILE *fp);
+
+/**
+ * @brief Print formatted number to \a fp.
+ *
+ * Prints the number \d to \a fp according to the specification \a spec.
+ *
+ * @param[in] spec Format specification.
+ * @param[in] num Number to print.
+ * @param[in] fp File to print to.
+ *
+ * @return Returns 0 on success.
+ */
+int xbps_fmt_number(const struct xbps_fmt_spec *spec, int64_t num, FILE *fp);
+
+/**
+ * @brief Print formatted string to \a fp.
+ *
+ * Prints the string \a str to \a fp according to the specification \a spec.
+ *
+ * @param[in] spec Format specification.
+ * @param[in] str String to print.
+ * @param[in] len Length of the string or 0.
+ * @param[in] fp File to print to.
+ *
+ * @return Returns 0 on success.
+ */
+int xbps_fmt_string(const struct xbps_fmt_spec *spec, const char *str, size_t len, FILE *fp);
+
+/**@}*/
+
 #ifdef __cplusplus
 }
 #endif

lib/Makefile

@@ -51,7 +51,7 @@ OBJS += plist_remove.o plist_fetch.o util.o util_path.o util_hash.o
 OBJS += repo.o repo_sync.o
 OBJS += rpool.o cb_util.o proplib_wrapper.o
 OBJS += package_alternatives.o
-OBJS += conf.o log.o
+OBJS += conf.o log.o format.o
 OBJS += $(EXTOBJS) $(COMPAT_OBJS)
 # unnecessary unless pkgdb format changes
 # OBJS += pkgdb_conversion.o