7z: support different archiver binaries

CHANGELOG

@@ -1,6 +1,7 @@
 next
 	- Support re-entry into previously-unpacked archive directory
 	- Support direct entry into directory with archive-like name
+	- Improved .7z support (use 7z/7zr/7za archiver as available)
 	- Fix minor no-recreate bug
 	- Fix .jar archive type recognition
 

README.md

@@ -47,7 +47,7 @@ Currently, it supports handling these file types:
   (requires tar with built-in support for these compression formats,
   i.e. the -zjJ options)
 * 7-zip
-  (requires **7zr** binary)
+  (requires **7z**/**7za**/**7zr** binary)
 * zip, jar
   (requires **zip** and **unzip** binaries)
 * rar

man/walk.1

@@ -38,7 +38,7 @@ tar, compressed with gzip/bzip2/xz
 i.e. the -zjJ options)
 .IP - 2
 7-zip
-(requires \fB7zr\fR binary)
+(requires \fB7z\fR/\fB7za\fR/\fB7zr\fR binary)
 .IP - 2
 zip, jar
 (requires \fBzip\fR and \fBunzip\fR binaries)

src/walk.sh

@@ -117,7 +117,7 @@ help () {
 	echo ""
 	echo "Recognized archive types:"
 	echo " - tar, tar.gz, tar.bz2, tar.xz (requires tar with built-in compression support)"
-	echo " - 7-zip (requires 7zr)"
+	echo " - 7-zip (requires 7z/7za/7zr)"
 	echo " - zip, jar (requires zip/unzip)"
 	echo " - rar (requires rar)"
 	echo " - cpio, ar"
@@ -320,8 +320,8 @@ archvtype () {
 			;;
 		"7-zip archive"*|"X-"*".7z")
 			z7opt="-bd -ms=on"
-			fn_unpack   () { 7zr x $z7opt "$1"   ; }
-			fn_pack     () { 7zr a $z7opt "$1" . ; }
+			fn_unpack   () { _7z x $z7opt "$1"   ; }
+			fn_pack     () { _7z a $z7opt "$1" . ; }
 			;;
 		*"rar archive"*|"X-"*".rar")
 			raropt="-o+ -ol -ow -r0 -tl"
@@ -396,6 +396,24 @@ test_reentry () {
 	false
 }
 
+findbin () {
+	# findbin BINARY...
+	#  Returns the path of the first BINARY that which(1) could find.
+	local list="$*"
+	while [ $# -gt 0 ]; do
+		which "$1" && return
+		shift
+	done
+	err "binary not found: $list"
+}
+
+_7z () {
+	local bin
+	bin=$(findbin 7z 7za 7zr) || return
+	"$bin" "$@"
+}
+
+
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