userdiff.c - jrn/git - Git at Google

 #include "cache.h"
 #include "userdiff.h"
 #include "cache.h"
 #include "attr.h"

 static struct userdiff_driver *drivers;
 static int ndrivers;
 static int drivers_alloc;

 #define PATTERNS(name, pattern, word_regex)			\
 	{ name, NULL, -1, { pattern, REG_EXTENDED },		\
 	  word_regex "|[^[:space:]]|[\xc0-\xff][\x80-\xbf]+" }
 #define IPATTERN(name, pattern, word_regex)			\
 	{ name, NULL, -1, { pattern, REG_EXTENDED | REG_ICASE }, \
 	  word_regex "|[^[:space:]]|[\xc0-\xff][\x80-\xbf]+" }
 static struct userdiff_driver builtin_drivers[] = {
 IPATTERN("fortran",
 	 "!^([C*]|[ \t]*!)\n"
 	 "!^[ \t]*MODULE[ \t]+PROCEDURE[ \t]\n"
 	 "^[ \t]*((END[ \t]+)?(PROGRAM|MODULE|BLOCK[ \t]+DATA"
 		"|([^'\" \t]+[ \t]+)*(SUBROUTINE|FUNCTION))[ \t]+[A-Z].*)$",
 	 /* -- */
 	 "[a-zA-Z][a-zA-Z0-9_]*"
 	 "|\\.([Ee][Qq]|[Nn][Ee]|[Gg][TtEe]|[Ll][TtEe]|[Tt][Rr][Uu][Ee]|[Ff][Aa][Ll][Ss][Ee]|[Aa][Nn][Dd]|[Oo][Rr]|[Nn]?[Ee][Qq][Vv]|[Nn][Oo][Tt])\\."
 	 /* numbers and format statements like 2E14.4, or ES12.6, 9X.
 	  * Don't worry about format statements without leading digits since
 	  * they would have been matched above as a variable anyway. */
 	 "|[-+]?[0-9.]+([AaIiDdEeFfLlTtXx][Ss]?[-+]?[0-9.]*)?(_[a-zA-Z0-9][a-zA-Z0-9_]*)?"
 	 "|//|\\*\\*|::|[/<>=]="),
 PATTERNS("html", "^[ \t]*(<[Hh][1-6][ \t].*>.*)$",
 	 "[^<>= \t]+"),
 PATTERNS("java",
 	 "!^[ \t]*(catch|do|for|if|instanceof|new|return|switch|throw|while)\n"
 	 "^[ \t]*(([A-Za-z_][A-Za-z_0-9]*[ \t]+)+[A-Za-z_][A-Za-z_0-9]*[ \t]*\\([^;]*)$",
 	 /* -- */
 	 "[a-zA-Z_][a-zA-Z0-9_]*"
 	 "|[-+0-9.e]+[fFlL]?|0[xXbB]?[0-9a-fA-F]+[lL]?"
 	 "|[-+*/<>%&^|=!]="
 	 "|--|\\+\\+|<<=?|>>>?=?|&&|\\|\\|"),
 PATTERNS("objc",
 	 /* Negate C statements that can look like functions */
 	 "!^[ \t]*(do|for|if|else|return|switch|while)\n"
 	 /* Objective-C methods */
 	 "^[ \t]*([-+][ \t]*\\([ \t]*[A-Za-z_][A-Za-z_0-9* \t]*\\)[ \t]*[A-Za-z_].*)$\n"
 	 /* C functions */
 	 "^[ \t]*(([A-Za-z_][A-Za-z_0-9]*[ \t]+)+[A-Za-z_][A-Za-z_0-9]*[ \t]*\\([^;]*)$\n"
 	 /* Objective-C class/protocol definitions */
 	 "^(@(implementation|interface|protocol)[ \t].*)$",
 	 /* -- */
 	 "[a-zA-Z_][a-zA-Z0-9_]*"
 	 "|[-+0-9.e]+[fFlL]?|0[xXbB]?[0-9a-fA-F]+[lL]?"
 	 "|[-+*/<>%&^|=!]=|--|\\+\\+|<<=?|>>=?|&&|\\|\\||::|->"),
 PATTERNS("pascal",
 	 "^(((class[ \t]+)?(procedure|function)|constructor|destructor|interface|"
 		"implementation|initialization|finalization)[ \t]*.*)$"
 	 "\n"
 	 "^(.*=[ \t]*(class|record).*)$",
 	 /* -- */
 	 "[a-zA-Z_][a-zA-Z0-9_]*"
 	 "|[-+0-9.e]+|0[xXbB]?[0-9a-fA-F]+"
 	 "|<>|<=|>=|:=|\\.\\."),
 PATTERNS("perl",
 	 "^[ \t]*package .*;\n"
 	 "^[ \t]*sub .* \\{\n"
 	 "^[A-Z]+ \\{\n"	/* BEGIN, END, ... */
 	 "^=head[0-9] ",	/* POD */
 	 /* -- */
 	 "[[:alpha:]_'][[:alnum:]_']*"
 	 "|0[xb]?[0-9a-fA-F_]*"
 	 /* taking care not to interpret 3..5 as (3.)(.5) */
 	 "|[0-9a-fA-F_]+(\\.[0-9a-fA-F_]+)?([eE][-+]?[0-9_]+)?"
 	 "|=>|-[rwxoRWXOezsfdlpSugkbctTBMAC>]|~~|::"
 	 "|&&=|\\|\\|=|//=|\\*\\*="
 	 "|&&|\\|\\||//|\\+\\+|--|\\*\\*|\\.\\.\\.?"
 	 "|[-+*/%.^&<>=!|]="
 	 "|=~|!~"
 	 "|<<|<>|<=>|>>"),
 PATTERNS("php",
 	 "^[\t ]*(((public|protected|private|static)[\t ]+)*function.*)$\n"
 	 "^[\t ]*(class.*)$",
 	 /* -- */
 	 "[a-zA-Z_][a-zA-Z0-9_]*"
 	 "|[-+0-9.e]+|0[xXbB]?[0-9a-fA-F]+"
 	 "|[-+*/<>%&^|=!.]=|--|\\+\\+|<<=?|>>=?|===|&&|\\|\\||::|->"),
 PATTERNS("python", "^[ \t]*((class|def)[ \t].*)$",
 	 /* -- */
 	 "[a-zA-Z_][a-zA-Z0-9_]*"
 	 "|[-+0-9.e]+[jJlL]?|0[xX]?[0-9a-fA-F]+[lL]?"
 	 "|[-+*/<>%&^|=!]=|//=?|<<=?|>>=?|\\*\\*=?"),
 	 /* -- */
 PATTERNS("ruby", "^[ \t]*((class|module|def)[ \t].*)$",
 	 /* -- */
 	 "(@|@@|\\$)?[a-zA-Z_][a-zA-Z0-9_]*"
 	 "|[-+0-9.e]+|0[xXbB]?[0-9a-fA-F]+|\\?(\\\\C-)?(\\\\M-)?."
 	 "|//=?|[-+*/<>%&^|=!]=|<<=?|>>=?|===|\\.{1,3}|::|[!=]~"),
 PATTERNS("bibtex", "(@[a-zA-Z]{1,}[ \t]*\\{{0,1}[ \t]*[^ \t\"@',\\#}{~%]*).*$",
 	 "[={}\"]|[^={}\" \t]+"),
 PATTERNS("tex", "^(\\\\((sub)*section|chapter|part)\\*{0,1}\\{.*)$",
 	 "\\\\[a-zA-Z@]+|\\\\.|[a-zA-Z0-9\x80-\xff]+"),
 PATTERNS("cpp",
 	 /* Jump targets or access declarations */
 	 "!^[ \t]*[A-Za-z_][A-Za-z_0-9]*:.*$\n"
 	 /* C/++ functions/methods at top level */
 	 "^([A-Za-z_][A-Za-z_0-9]*([ \t]+[A-Za-z_][A-Za-z_0-9]*([ \t]*::[ \t]*[^[:space:]]+)?){1,}[ \t]*\\([^;]*)$\n"
 	 /* compound type at top level */
 	 "^((struct|class|enum)[^;]*)$",
 	 /* -- */
 	 "[a-zA-Z_][a-zA-Z0-9_]*"
 	 "|[-+0-9.e]+[fFlL]?|0[xXbB]?[0-9a-fA-F]+[lL]?"
 	 "|[-+*/<>%&^|=!]=|--|\\+\\+|<<=?|>>=?|&&|\\|\\||::|->"),
 PATTERNS("csharp",
 	 /* Keywords */
 	 "!^[ \t]*(do|while|for|if|else|instanceof|new|return|switch|case|throw|catch|using)\n"
 	 /* Methods and constructors */
 	 "^[ \t]*(((static|public|internal|private|protected|new|virtual|sealed|override|unsafe)[ \t]+)*[][<>@.~_[:alnum:]]+[ \t]+[<>@._[:alnum:]]+[ \t]*\\(.*\\))[ \t]*$\n"
 	 /* Properties */
 	 "^[ \t]*(((static|public|internal|private|protected|new|virtual|sealed|override|unsafe)[ \t]+)*[][<>@.~_[:alnum:]]+[ \t]+[@._[:alnum:]]+)[ \t]*$\n"
 	 /* Type definitions */
 	 "^[ \t]*(((static|public|internal|private|protected|new|unsafe|sealed|abstract|partial)[ \t]+)*(class|enum|interface|struct)[ \t]+.*)$\n"
 	 /* Namespace */
 	 "^[ \t]*(namespace[ \t]+.*)$",
 	 /* -- */
 	 "[a-zA-Z_][a-zA-Z0-9_]*"
 	 "|[-+0-9.e]+[fFlL]?|0[xXbB]?[0-9a-fA-F]+[lL]?"
 	 "|[-+*/<>%&^|=!]=|--|\\+\\+|<<=?|>>=?|&&|\\|\\||::|->"),
 { "default", NULL, -1, { NULL, 0 } },
 };
 #undef PATTERNS
 #undef IPATTERN

 static struct userdiff_driver driver_true = {
 	"diff=true",
 	NULL,
 	0,
 	{ NULL, 0 }
 };

 static struct userdiff_driver driver_false = {
 	"!diff",
 	NULL,
 	1,
 	{ NULL, 0 }
 };

 static struct userdiff_driver *userdiff_find_by_namelen(const char *k, int len)
 {
 	int i;
 	for (i = 0; i < ndrivers; i++) {
 		struct userdiff_driver *drv = drivers + i;
 		if (!strncmp(drv->name, k, len) && !drv->name[len])
 			return drv;
 	}
 	for (i = 0; i < ARRAY_SIZE(builtin_drivers); i++) {
 		struct userdiff_driver *drv = builtin_drivers + i;
 		if (!strncmp(drv->name, k, len) && !drv->name[len])
 			return drv;
 	}
 	return NULL;
 }

 static struct userdiff_driver *parse_driver(const char *var,
 		const char *value, const char *type)
 {
 	struct userdiff_driver *drv;
 	const char *dot;
 	const char *name;
 	int namelen;

 	if (prefixcmp(var, "diff."))
 		return NULL;
 	dot = strrchr(var, '.');
 	if (dot == var + 4)
 		return NULL;
 	if (strcmp(type, dot+1))
 		return NULL;

 	name = var + 5;
 	namelen = dot - name;
 	drv = userdiff_find_by_namelen(name, namelen);
 	if (!drv) {
 		ALLOC_GROW(drivers, ndrivers+1, drivers_alloc);
 		drv = &drivers[ndrivers++];
 		memset(drv, 0, sizeof(*drv));
 		drv->name = xmemdupz(name, namelen);
 		drv->binary = -1;
 	}
 	return drv;
 }

 static int parse_funcname(struct userdiff_funcname *f, const char *k,
 		const char *v, int cflags)
 {
 	if (git_config_string(&f->pattern, k, v) < 0)
 		return -1;
 	f->cflags = cflags;
 	return 1;
 }

 static int parse_string(const char **d, const char *k, const char *v)
 {
 	if (git_config_string(d, k, v) < 0)
 		return -1;
 	return 1;
 }

 static int parse_tristate(int *b, const char *k, const char *v)
 {
 	if (v && !strcasecmp(v, "auto"))
 		*b = -1;
 	else
 		*b = git_config_bool(k, v);
 	return 1;
 }

 static int parse_bool(int *b, const char *k, const char *v)
 {
 	*b = git_config_bool(k, v);
 	return 1;
 }

 int userdiff_config(const char *k, const char *v)
 {
 	struct userdiff_driver *drv;

 	if ((drv = parse_driver(k, v, "funcname")))
 		return parse_funcname(&drv->funcname, k, v, 0);
 	if ((drv = parse_driver(k, v, "xfuncname")))
 		return parse_funcname(&drv->funcname, k, v, REG_EXTENDED);
 	if ((drv = parse_driver(k, v, "binary")))
 		return parse_tristate(&drv->binary, k, v);
 	if ((drv = parse_driver(k, v, "command")))
 		return parse_string(&drv->external, k, v);
 	if ((drv = parse_driver(k, v, "textconv")))
 		return parse_string(&drv->textconv, k, v);
 	if ((drv = parse_driver(k, v, "cachetextconv")))
 		return parse_bool(&drv->textconv_want_cache, k, v);
 	if ((drv = parse_driver(k, v, "wordregex")))
 		return parse_string(&drv->word_regex, k, v);

 	return 0;
 }

 struct userdiff_driver *userdiff_find_by_name(const char *name) {
 	int len = strlen(name);
 	return userdiff_find_by_namelen(name, len);
 }

 struct userdiff_driver *userdiff_find_by_path(const char *path)
 {
 	static struct git_attr *attr;
 	struct git_attr_check check;

 	if (!attr)
 		attr = git_attr("diff");
 	check.attr = attr;

 	if (!path)
 		return NULL;
 	if (git_checkattr(path, 1, &check))
 		return NULL;

 	if (ATTR_TRUE(check.value))
 		return &driver_true;
 	if (ATTR_FALSE(check.value))
 		return &driver_false;
 	if (ATTR_UNSET(check.value))
 		return NULL;
 	return userdiff_find_by_name(check.value);
 }
	#include "cache.h"
	#include "userdiff.h"
	#include "cache.h"
	#include "attr.h"

	static struct userdiff_driver *drivers;
	static int ndrivers;
	static int drivers_alloc;

	#define PATTERNS(name, pattern, word_regex) \
	{ name, NULL, -1, { pattern, REG_EXTENDED }, \
	word_regex "\|[^[:space:]]\|[\xc0-\xff][\x80-\xbf]+" }
	#define IPATTERN(name, pattern, word_regex) \
	{ name, NULL, -1, { pattern, REG_EXTENDED \| REG_ICASE }, \
	word_regex "\|[^[:space:]]\|[\xc0-\xff][\x80-\xbf]+" }
	static struct userdiff_driver builtin_drivers[] = {
	IPATTERN("fortran",
	"!^([C]\|[ \t]!)\n"
	"!^[ \t]*MODULE[ \t]+PROCEDURE[ \t]\n"
	"^[ \t]*((END[ \t]+)?(PROGRAM\|MODULE\|BLOCK[ \t]+DATA"
	"\|([^'\" \t]+[ \t]+)(SUBROUTINE\|FUNCTION))[ \t]+[A-Z].)$",
	/* -- */
	"[a-zA-Z][a-zA-Z0-9_]*"
	"\|\\.([Ee][Qq]\|[Nn][Ee]\|[Gg][TtEe]\|[Ll][TtEe]\|[Tt][Rr][Uu][Ee]\|[Ff][Aa][Ll][Ss][Ee]\|[Aa][Nn][Dd]\|[Oo][Rr]\|[Nn]?[Ee][Qq][Vv]\|[Nn][Oo][Tt])\\."
	/* numbers and format statements like 2E14.4, or ES12.6, 9X.
	* Don't worry about format statements without leading digits since
	* they would have been matched above as a variable anyway. */
	"\|[-+]?[0-9.]+([AaIiDdEeFfLlTtXx][Ss]?[-+]?[0-9.])?(_[a-zA-Z0-9][a-zA-Z0-9_])?"
	"\|//\|\\\\\|::\|[/<>=]="),
	PATTERNS("html", "^[ \t](<[Hh][1-6][ \t].>.*)$",
	"[^<>= \t]+"),
	PATTERNS("java",
	"!^[ \t]*(catch\|do\|for\|if\|instanceof\|new\|return\|switch\|throw\|while)\n"
	"^[ \t](([A-Za-z_][A-Za-z_0-9][ \t]+)+[A-Za-z_][A-Za-z_0-9][ \t]\\([^;]*)$",
	/* -- */
	"[a-zA-Z_][a-zA-Z0-9_]*"
	"\|[-+0-9.e]+[fFlL]?\|0[xXbB]?[0-9a-fA-F]+[lL]?"
	"\|[-+*/<>%&^\|=!]="
	"\|--\|\\+\\+\|<<=?\|>>>?=?\|&&\|\\\|\\\|"),
	PATTERNS("objc",
	/* Negate C statements that can look like functions */
	"!^[ \t]*(do\|for\|if\|else\|return\|switch\|while)\n"
	/* Objective-C methods */
	"^[ \t]([-+][ \t]\\([ \t][A-Za-z_][A-Za-z_0-9 \t]\\)[ \t][A-Za-z_].*)$\n"
	/* C functions */
	"^[ \t](([A-Za-z_][A-Za-z_0-9][ \t]+)+[A-Za-z_][A-Za-z_0-9][ \t]\\([^;]*)$\n"
	/* Objective-C class/protocol definitions */
	"^(@(implementation\|interface\|protocol)[ \t].*)$",
	/* -- */
	"[a-zA-Z_][a-zA-Z0-9_]*"
	"\|[-+0-9.e]+[fFlL]?\|0[xXbB]?[0-9a-fA-F]+[lL]?"
	"\|[-+*/<>%&^\|=!]=\|--\|\\+\\+\|<<=?\|>>=?\|&&\|\\\|\\\|\|::\|->"),
	PATTERNS("pascal",
	"^(((class[ \t]+)?(procedure\|function)\|constructor\|destructor\|interface\|"
	"implementation\|initialization\|finalization)[ \t].)$"
	"\n"
	"^(.=[ \t](class\|record).*)$",
	/* -- */
	"[a-zA-Z_][a-zA-Z0-9_]*"
	"\|[-+0-9.e]+\|0[xXbB]?[0-9a-fA-F]+"
	"\|<>\|<=\|>=\|:=\|\\.\\."),
	PATTERNS("perl",
	"^[ \t]package .;\n"
	"^[ \t]sub . \\{\n"
	"^[A-Z]+ \\{\n" /* BEGIN, END, ... */
	"^=head[0-9] ", /* POD */
	/* -- */
	"[[:alpha:]_'][[:alnum:]_']*"
	"\|0[xb]?[0-9a-fA-F_]*"
	/* taking care not to interpret 3..5 as (3.)(.5) */
	"\|[0-9a-fA-F_]+(\\.[0-9a-fA-F_]+)?([eE][-+]?[0-9_]+)?"
	"\|=>\|-[rwxoRWXOezsfdlpSugkbctTBMAC>]\|~~\|::"
	"\|&&=\|\\\|\\\|=\|//=\|\\\\="
	"\|&&\|\\\|\\\|\|//\|\\+\\+\|--\|\\\\\|\\.\\.\\.?"
	"\|[-+*/%.^&<>=!\|]="
	"\|=~\|!~"
	"\|<<\|<>\|<=>\|>>"),
	PATTERNS("php",
	"^[\t ](((public\|protected\|private\|static)[\t ]+)function.*)$\n"
	"^[\t ](class.)$",
	/* -- */
	"[a-zA-Z_][a-zA-Z0-9_]*"
	"\|[-+0-9.e]+\|0[xXbB]?[0-9a-fA-F]+"
	"\|[-+*/<>%&^\|=!.]=\|--\|\\+\\+\|<<=?\|>>=?\|===\|&&\|\\\|\\\|\|::\|->"),
	PATTERNS("python", "^[ \t]((class\|def)[ \t].)$",
	/* -- */
	"[a-zA-Z_][a-zA-Z0-9_]*"
	"\|[-+0-9.e]+[jJlL]?\|0[xX]?[0-9a-fA-F]+[lL]?"
	"\|[-+/<>%&^\|=!]=\|//=?\|<<=?\|>>=?\|\\\\*=?"),
	/* -- */
	PATTERNS("ruby", "^[ \t]((class\|module\|def)[ \t].)$",
	/* -- */
	"(@\|@@\|\\$)?[a-zA-Z_][a-zA-Z0-9_]*"
	"\|[-+0-9.e]+\|0[xXbB]?[0-9a-fA-F]+\|\\?(\\\\C-)?(\\\\M-)?."
	"\|//=?\|[-+*/<>%&^\|=!]=\|<<=?\|>>=?\|===\|\\.{1,3}\|::\|[!=]~"),
	PATTERNS("bibtex", "(@[a-zA-Z]{1,}[ \t]\\{{0,1}[ \t][^ \t\"@',\\#}{~%]).$",
	"[={}\"]\|[^={}\" \t]+"),
	PATTERNS("tex", "^(\\\\((sub)section\|chapter\|part)\\{0,1}\\{.*)$",
	"\\\\[a-zA-Z@]+\|\\\\.\|[a-zA-Z0-9\x80-\xff]+"),
	PATTERNS("cpp",
	/* Jump targets or access declarations */
	"!^[ \t][A-Za-z_][A-Za-z_0-9]:.*$\n"
	/* C/++ functions/methods at top level */
	"^([A-Za-z_][A-Za-z_0-9]([ \t]+[A-Za-z_][A-Za-z_0-9]([ \t]::[ \t][^[:space:]]+)?){1,}[ \t]\\([^;])$\n"
	/* compound type at top level */
	"^((struct\|class\|enum)[^;]*)$",
	/* -- */
	"[a-zA-Z_][a-zA-Z0-9_]*"
	"\|[-+0-9.e]+[fFlL]?\|0[xXbB]?[0-9a-fA-F]+[lL]?"
	"\|[-+*/<>%&^\|=!]=\|--\|\\+\\+\|<<=?\|>>=?\|&&\|\\\|\\\|\|::\|->"),
	PATTERNS("csharp",
	/* Keywords */
	"!^[ \t]*(do\|while\|for\|if\|else\|instanceof\|new\|return\|switch\|case\|throw\|catch\|using)\n"
	/* Methods and constructors */
	"^[ \t](((static\|public\|internal\|private\|protected\|new\|virtual\|sealed\|override\|unsafe)[ \t]+)[][<>@.~_[:alnum:]]+[ \t]+[<>@._[:alnum:]]+[ \t]\\(.\\))[ \t]*$\n"
	/* Properties */
	"^[ \t](((static\|public\|internal\|private\|protected\|new\|virtual\|sealed\|override\|unsafe)[ \t]+)[][<>@.~_[:alnum:]]+[ \t]+[@._[:alnum:]]+)[ \t]*$\n"
	/* Type definitions */
	"^[ \t](((static\|public\|internal\|private\|protected\|new\|unsafe\|sealed\|abstract\|partial)[ \t]+)(class\|enum\|interface\|struct)[ \t]+.*)$\n"
	/* Namespace */
	"^[ \t](namespace[ \t]+.)$",
	/* -- */
	"[a-zA-Z_][a-zA-Z0-9_]*"
	"\|[-+0-9.e]+[fFlL]?\|0[xXbB]?[0-9a-fA-F]+[lL]?"
	"\|[-+*/<>%&^\|=!]=\|--\|\\+\\+\|<<=?\|>>=?\|&&\|\\\|\\\|\|::\|->"),
	{ "default", NULL, -1, { NULL, 0 } },
	};
	#undef PATTERNS
	#undef IPATTERN

	static struct userdiff_driver driver_true = {
	"diff=true",
	NULL,
	0,
	{ NULL, 0 }
	};

	static struct userdiff_driver driver_false = {
	"!diff",
	NULL,
	1,
	{ NULL, 0 }
	};

	static struct userdiff_driver userdiff_find_by_namelen(const char k, int len)
	{
	int i;
	for (i = 0; i < ndrivers; i++) {
	struct userdiff_driver *drv = drivers + i;
	if (!strncmp(drv->name, k, len) && !drv->name[len])
	return drv;
	}
	for (i = 0; i < ARRAY_SIZE(builtin_drivers); i++) {
	struct userdiff_driver *drv = builtin_drivers + i;
	if (!strncmp(drv->name, k, len) && !drv->name[len])
	return drv;
	}
	return NULL;
	}

	static struct userdiff_driver parse_driver(const char var,
	const char value, const char type)
	{
	struct userdiff_driver *drv;
	const char *dot;
	const char *name;
	int namelen;

	if (prefixcmp(var, "diff."))
	return NULL;
	dot = strrchr(var, '.');
	if (dot == var + 4)
	return NULL;
	if (strcmp(type, dot+1))
	return NULL;

	name = var + 5;
	namelen = dot - name;
	drv = userdiff_find_by_namelen(name, namelen);
	if (!drv) {
	ALLOC_GROW(drivers, ndrivers+1, drivers_alloc);
	drv = &drivers[ndrivers++];
	memset(drv, 0, sizeof(*drv));
	drv->name = xmemdupz(name, namelen);
	drv->binary = -1;
	}
	return drv;
	}

	static int parse_funcname(struct userdiff_funcname f, const char k,
	const char *v, int cflags)
	{
	if (git_config_string(&f->pattern, k, v) < 0)
	return -1;
	f->cflags = cflags;
	return 1;
	}

	static int parse_string(const char *d, const char k, const char *v)
	{
	if (git_config_string(d, k, v) < 0)
	return -1;
	return 1;
	}

	static int parse_tristate(int b, const char k, const char *v)
	{
	if (v && !strcasecmp(v, "auto"))
	*b = -1;
	else
	*b = git_config_bool(k, v);
	return 1;
	}

	static int parse_bool(int b, const char k, const char *v)
	{
	*b = git_config_bool(k, v);
	return 1;
	}

	int userdiff_config(const char k, const char v)
	{
	struct userdiff_driver *drv;

	if ((drv = parse_driver(k, v, "funcname")))
	return parse_funcname(&drv->funcname, k, v, 0);
	if ((drv = parse_driver(k, v, "xfuncname")))
	return parse_funcname(&drv->funcname, k, v, REG_EXTENDED);
	if ((drv = parse_driver(k, v, "binary")))
	return parse_tristate(&drv->binary, k, v);
	if ((drv = parse_driver(k, v, "command")))
	return parse_string(&drv->external, k, v);
	if ((drv = parse_driver(k, v, "textconv")))
	return parse_string(&drv->textconv, k, v);
	if ((drv = parse_driver(k, v, "cachetextconv")))
	return parse_bool(&drv->textconv_want_cache, k, v);
	if ((drv = parse_driver(k, v, "wordregex")))
	return parse_string(&drv->word_regex, k, v);

	return 0;
	}

	struct userdiff_driver userdiff_find_by_name(const char name) {
	int len = strlen(name);
	return userdiff_find_by_namelen(name, len);
	}

	struct userdiff_driver userdiff_find_by_path(const char path)
	{
	static struct git_attr *attr;
	struct git_attr_check check;

	if (!attr)
	attr = git_attr("diff");
	check.attr = attr;

	if (!path)
	return NULL;
	if (git_checkattr(path, 1, &check))
	return NULL;

	if (ATTR_TRUE(check.value))
	return &driver_true;
	if (ATTR_FALSE(check.value))
	return &driver_false;
	if (ATTR_UNSET(check.value))
	return NULL;
	return userdiff_find_by_name(check.value);
	}