Support cross compiling

.gitignore

@@ -1,5 +1,6 @@
 *.d
 *.o
+*.dSYM
 Makefile
 TAGS
 tags

Makefile.in

@@ -37,7 +37,7 @@ INSTALL_DIR = @INSTALL_DIR@
 ARCHIVER = @ARCHIVER@
 DIRS = @DIRS@
 SOURCES = alias.c arith.c builtin.c exec.c expand.c hashtable.c history.c input.c job.c mail.c makesignum.c option.c parser.c path.c plist.c redir.c sig.c strbuf.c util.c variable.c xfnmatch.c xgetopt.c yash.c
-HEADERS = alias.h arith.h builtin.h common.h exec.h expand.h hashtable.h history.h input.h job.h mail.h option.h parser.h path.h plist.h redir.h refcount.h sig.h siglist.h strbuf.h util.h variable.h xfnmatch.h xgetopt.h yash.h
+HEADERS = alias.h arith.h builtin.h common.h cross-signum.h exec.h expand.h hashtable.h history.h input.h job.h mail.h option.h parser.h path.h plist.h redir.h refcount.h sig.h siglist.h strbuf.h util.h variable.h xfnmatch.h xgetopt.h yash.h
 MAIN_OBJS = alias.o arith.o builtin.o exec.o expand.o hashtable.o input.o job.o mail.o option.o parser.o path.o plist.o redir.o sig.o strbuf.o util.o variable.o xfnmatch.o xgetopt.o yash.o
 HISTORY_OBJS = history.o
 BUILTINS_ARCHIVE = builtins/builtins.a
@@ -80,7 +80,7 @@ makesignum:
 	$(CC) $(CFLAGS) $(CPPFLAGS) $(LDFLAGS) -o $@ $@.c $(LDLIBS)
 sig.o: signum.h
 signum.h: makesignum
-	./makesignum > $@
+	./makesignum > $@ 2> /dev/null || cp cross-signum.h $@
 variable.o yash.o: configm.h
 configm.h: Makefile
 	-@printf 'creating %s...' '$@'

configure

@@ -123,6 +123,10 @@ do
             nocreate="true" ;;
         -d|--debug)
             debug="true" ;;
+        --host=*)
+            host="${i#--host=}" ;;
+        --build=*) # included for autoconf compatibility, does nothing
+            ;;
         --prefix=*)
             prefix="${i#--prefix=}" ;;
         --exec-prefix=*)
@@ -151,7 +155,7 @@ do
             term_lib="${i#--with-term-lib=}" ;;
         ?*=*)
             # parse variable assignment
-            if echo "$i" | grep -E "^[[:alpha:]][[:alnum:]]*=" >/dev/null
+            if printf '%s\n' "$i" | grep -Eq "^[[:alpha:]][[:alnum:]_]*="
             then
                 export "$i"
             else
@@ -173,6 +177,7 @@ Usage: sh $0 [options...]
 Available options:
   --no-create            do not create output files
   --debug                configure for debug build (GCC or Clang required)
+  --host=HOST            sets the prefix for build tools to HOST
 
 Installation options:
   --prefix=PREFIX        install architecture-independent files in PREFIX
@@ -214,7 +219,8 @@ Influential environment variables:
   MSGMERGEFLAGS, MSGINIT, MSGCONV, MSGFILTER,
   ASCIIDOC, ASCIIDOCFLAGS, ASCIIDOCATTRS, A2X, A2XFLAGS,
   INSTALL, INSTALL_PROGRAM, INSTALL_DATA, INSTALL_DIR,
-  CTAGS, CTAGSARGS, ETAGS, ETAGSARGS, CSCOPE, CSCOPEARGS
+  CTAGS, CTAGSARGS, ETAGS, ETAGSARGS, CSCOPE, CSCOPEARGS,
+  YASH_GETCWD_AUTO_MALLOC
 END
     exit
 fi
@@ -291,7 +297,12 @@ trylink () {
         -o "${tempout}" "${tempo}" "$@" ${LDLIBS-${ldlibs}}
 }
 tryexec () {
-    checkby "${tempout}"
+    if ${cross_compiling}; then
+        checkresult="yes"
+        return 0
+    else
+        checkby "${tempout}"
+    fi
 }
 checked () {
     if [ $# -ge 1 ]
@@ -311,13 +322,13 @@ fail () {
     exit 1
 }
 
-
-cc="${CC-c99}"
+[ -n "$host" ] && _host="$host-"
+cc="${CC-${_host}c99}"
+ar="${AR-${_host}ar}"
 cflags="${CFLAGS--O1 -g}"
 cppflags="${CPPFLAGS-${null}}"
 ldflags="${LDFLAGS-${null}}"
 ldlibs="${LDLIBS-${null}}"
-ar="${AR-ar}"
 arflags="${ARFLAGS--rc}"
 xgettext="${XGETTEXT-xgettext}"
 xgettextflags="${XGETTEXTFLAGS--kgt -kNgt -kngt:1,2 \
@@ -344,10 +355,87 @@ cscope="${CSCOPE-cscope}"
 
 confighdefs=''
 
+# define options for debugging
+if ${debug}
+then
+    cflags="${CFLAGS--pedantic -MMD -Wall -Wextra -Og -fno-inline -ggdb}"
+else
+    defconfigh "NDEBUG"
+fi
+
+
+# check if the compiler works
+checking 'whether the compiler works'
+cat >"${tempsrc}" <<END
+int main(void) { return 0; }
+END
+if
+    trymake
+then
+    checked "yes"
+elif
+    [ x"${cc}" = x"${_host}c99" ] && [ x"${CC+set}" != x"set" ] && (
+        cc="${_host}gcc"
+        trymake
+    )
+then
+    cc="${_host}gcc"
+    checked "yes (using $cc)"
+elif
+    [ x"${cc}" = x"${_host}c99" ] && [ x"${CC+set}" != x"set" ] && (
+        cc="${_host}clang"
+        trymake
+    )
+then
+    cc="${_host}clang"
+    checked "yes (using $cc)"
+else
+    checked "no"
+    printf 'Compiler "%s" not found or not working.\n' "${CC-${cc}}" >&2
+    printf 'The compiler is expected to accept these options: %s\n' \
+        "${CFLAGS-${cflags}} ${CADDS-${null}}" >&2
+    fail
+fi
+
+# check if we are cross compiling
+checking 'whether we are cross compiling'
+cross_compiling=false
+if
+    tryexec
+then
+    checked "no"
+else
+    checked "yes"
+    cross_compiling=true
+fi
 
 # check OS type
 checking 'operating system'
-ostype=$(uname -s | tr "[:upper:]" "[:lower:]")
+if $cross_compiling; then
+    # this is a list of every os that affects the build, if you add a check like
+    # 'if [ "$ostype" = "foo" ]' to the configure script than 'foo' would need
+    # to be added to this list so it can be detected, otherwise we just set
+    # $ostype to 'unknown' and hope for the best.
+    for os in darwin freebsd sunos solaris
+    do
+        case "$host" in
+            *"$os"*)
+                ostype="$os"
+                break
+        esac
+    done
+    # sometimes there are common os names used for targets that differ from what
+    # 'uname -s' outputs, those are caught here and corrected.
+    case $ostype in
+        solaris)
+            ostype='sunos'
+            ;;
+    esac
+    [ -z "$ostype" ] && ostype='unknown'
+else
+    ostype=$(uname -s | tr "[:upper:]" "[:lower:]")
+fi
+
 checked "${ostype}"
 case "${ostype}" in
     darwin)
@@ -358,26 +446,35 @@ case "${ostype}" in
         ;;
 esac
 
-
 # check POSIX conformance
 checking 'POSIX conformance'
-posixver=$(getconf _POSIX_VERSION 2>/dev/null)
-if [ -n "${posixver}" ] && [ x"${posixver}" != x"undefined" ]
-then
-    checked "${posixver}"
+if ${cross_compiling}; then
+    checked "guessing 200112"
+    posixver="200112"
 else
-    checked "no"
-    posixver=""
+    posixver=$(getconf _POSIX_VERSION 2>/dev/null)
+    if [ -n "${posixver}" ] && [ x"${posixver}" != x"undefined" ]
+    then
+        checked "${posixver}"
+    else
+        checked "no"
+        posixver=""
+    fi
 fi
 
 checking 'SUS conformance'
-xopenver=$(getconf _XOPEN_VERSION 2>/dev/null)
-if [ -n "${xopenver}" ] && [ x"${xopenver}" != x"undefined" ]
-then
-    checked "${xopenver}"
+if ${cross_compiling}; then
+    checked "guessing 600"
+    xopenver="600"
 else
-    checked "no"
-    xopenver=""
+    xopenver=$(getconf _XOPEN_VERSION 2>/dev/null)
+    if [ -n "${xopenver}" ] && [ x"${xopenver}" != x"undefined" ]
+    then
+        checked "${xopenver}"
+    else
+        checked "no"
+        xopenver=""
+    fi
 fi
 
 case "${ostype}" in
@@ -394,49 +491,6 @@ case "${ostype}" in
         ;;
 esac
 
-
-# define options for debugging
-if ${debug}
-then
-    cflags="${CFLAGS--pedantic -MMD -Wall -Wextra -Og -fno-inline -ggdb}"
-else
-    defconfigh "NDEBUG"
-fi
-
-
-# check if the compiler works
-checking 'whether the compiler works'
-cat >"${tempsrc}" <<END
-int main(void) { return 0; }
-END
-if
-    trymake && tryexec
-then
-    checked "yes"
-elif
-    [ x"${cc}" = x"c99" ] && [ x"${CC+set}" != x"set" ] && (
-        cc='gcc'
-        trymake && tryexec
-    )
-then
-    checked "yes (using gcc)"
-    cc='gcc'
-elif
-    [ x"${cc}" = x"c99" ] && [ x"${CC+set}" != x"set" ] && (
-        cc='clang'
-        trymake && tryexec
-    )
-then
-    checked "yes (using clang)"
-    cc='clang'
-else
-    checked "no"
-    printf 'Compiler "%s" not found or not working.\n' "${CC-${cc}}" >&2
-    printf 'The compiler is expected to accept these options: %s\n' \
-        "${CFLAGS-${cflags}} ${CADDS-${null}}" >&2
-    fail
-fi
-
 # check if the compiler accepts the -O2 option if we are not debugging
 if ! ${debug} && [ x"${CFLAGS+set}" != x"set" ]
 then
@@ -1417,7 +1471,8 @@ fi
 
 # check if getcwd accepts (NULL,0) as argument
 checking "if getcwd(NULL,0) returns malloc'ed string"
-cat >"${tempsrc}" <<END
+if [ -z "$YASH_GETCWD_AUTO_MALLOC" ]; then
+    cat >"${tempsrc}" <<END
 ${confighdefs}
 #include <errno.h>
 #include <stdlib.h>
@@ -1450,8 +1505,16 @@ int main(void) {
     free(wd11); free(wd2); return 0;
 }
 END
-trymake && tryexec
-checked
+    if ${cross_compiling}; then
+        checked "assuming no"
+        checkresult="no"
+    else
+        trymake && tryexec
+        checked
+    fi
+else
+    checked "$YASH_GETCWD_AUTO_MALLOC"
+fi
 if [ x"${checkresult}" = x"yes" ]
 then
     defconfigh "GETCWD_AUTO_MALLOC"