Initial revision

1 files changed, 734 insertions, 0 deletions

diff --git a/generic/tclPkg.c b/generic/tclPkg.c
new file mode 100644
index 0000000..4a58eac
--- /dev/null
+++ b/generic/tclPkg.c
@@ -0,0 +1,734 @@
+/* 
+ * tclPkg.c --
+ *
+ *	This file implements package and version control for Tcl via
+ *	the "package" command and a few C APIs.
+ *
+ * Copyright (c) 1996 Sun Microsystems, Inc.
+ *
+ * See the file "license.terms" for information on usage and redistribution
+ * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
+ *
+ * SCCS: @(#) tclPkg.c 1.9 97/05/14 13:23:51
+ */
+
+#include "tclInt.h"
+
+/*
+ * Each invocation of the "package ifneeded" command creates a structure
+ * of the following type, which is used to load the package into the
+ * interpreter if it is requested with a "package require" command.
+ */
+
+typedef struct PkgAvail {
+    char *version;		/* Version string; malloc'ed. */
+    char *script;		/* Script to invoke to provide this version
+				 * of the package.  Malloc'ed and protected
+				 * by Tcl_Preserve and Tcl_Release. */
+    struct PkgAvail *nextPtr;	/* Next in list of available versions of
+				 * the same package. */
+} PkgAvail;
+
+/*
+ * For each package that is known in any way to an interpreter, there
+ * is one record of the following type.  These records are stored in
+ * the "packageTable" hash table in the interpreter, keyed by
+ * package name such as "Tk" (no version number).
+ */
+
+typedef struct Package {
+    char *version;		/* Version that has been supplied in this
+				 * interpreter via "package provide"
+				 * (malloc'ed).  NULL means the package doesn't
+				 * exist in this interpreter yet. */
+    PkgAvail *availPtr;		/* First in list of all available versions
+				 * of this package. */
+} Package;
+
+/*
+ * Prototypes for procedures defined in this file:
+ */
+
+static int		CheckVersion _ANSI_ARGS_((Tcl_Interp *interp,
+			    char *string));
+static int		ComparePkgVersions _ANSI_ARGS_((char *v1, char *v2,
+			    int *satPtr));
+static Package *	FindPackage _ANSI_ARGS_((Tcl_Interp *interp,
+			    char *name));
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_PkgProvide --
+ *
+ *	This procedure is invoked to declare that a particular version
+ *	of a particular package is now present in an interpreter.  There
+ *	must not be any other version of this package already
+ *	provided in the interpreter.
+ *
+ * Results:
+ *	Normally returns TCL_OK;  if there is already another version
+ *	of the package loaded then TCL_ERROR is returned and an error
+ *	message is left in interp->result.
+ *
+ * Side effects:
+ *	The interpreter remembers that this package is available,
+ *	so that no other version of the package may be provided for
+ *	the interpreter.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+Tcl_PkgProvide(interp, name, version)
+    Tcl_Interp *interp;		/* Interpreter in which package is now
+				 * available. */
+    char *name;			/* Name of package. */
+    char *version;		/* Version string for package. */
+{
+    Package *pkgPtr;
+
+    pkgPtr = FindPackage(interp, name);
+    if (pkgPtr->version == NULL) {
+	pkgPtr->version = ckalloc((unsigned) (strlen(version) + 1));
+	strcpy(pkgPtr->version, version);
+	return TCL_OK;
+    }
+    if (ComparePkgVersions(pkgPtr->version, version, (int *) NULL) == 0) {
+	return TCL_OK;
+    }
+    Tcl_AppendResult(interp, "conflicting versions provided for package \"",
+	    name, "\": ", pkgPtr->version, ", then ", version, (char *) NULL);
+    return TCL_ERROR;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_PkgRequire --
+ *
+ *	This procedure is called by code that depends on a particular
+ *	version of a particular package.  If the package is not already
+ *	provided in the interpreter, this procedure invokes a Tcl script
+ *	to provide it.  If the package is already provided, this
+ *	procedure makes sure that the caller's needs don't conflict with
+ *	the version that is present.
+ *
+ * Results:
+ *	If successful, returns the version string for the currently
+ *	provided version of the package, which may be different from
+ *	the "version" argument.  If the caller's requirements
+ *	cannot be met (e.g. the version requested conflicts with
+ *	a currently provided version, or the required version cannot
+ *	be found, or the script to provide the required version
+ *	generates an error), NULL is returned and an error
+ *	message is left in interp->result.
+ *
+ * Side effects:
+ *	The script from some previous "package ifneeded" command may
+ *	be invoked to provide the package.
+ *
+ *----------------------------------------------------------------------
+ */
+
+char *
+Tcl_PkgRequire(interp, name, version, exact)
+    Tcl_Interp *interp;		/* Interpreter in which package is now
+				 * available. */
+    char *name;			/* Name of desired package. */
+    char *version;		/* Version string for desired version;
+				 * NULL means use the latest version
+				 * available. */
+    int exact;			/* Non-zero means that only the particular
+				 * version given is acceptable. Zero means
+				 * use the latest compatible version. */
+{
+    Package *pkgPtr;
+    PkgAvail *availPtr, *bestPtr;
+    char *script;
+    int code, satisfies, result, pass;
+    Tcl_DString command;
+
+    /*
+     * It can take up to three passes to find the package:  one pass to
+     * run the "package unknown" script, one to run the "package ifneeded"
+     * script for a specific version, and a final pass to lookup the
+     * package loaded by the "package ifneeded" script.
+     */
+
+    for (pass = 1; ; pass++) {
+	pkgPtr = FindPackage(interp, name);
+	if (pkgPtr->version != NULL) {
+	    break;
+	}
+
+	/*
+	 * The package isn't yet present.  Search the list of available
+	 * versions and invoke the script for the best available version.
+	 */
+    
+	bestPtr = NULL;
+	for (availPtr = pkgPtr->availPtr; availPtr != NULL;
+		availPtr = availPtr->nextPtr) {
+	    if ((bestPtr != NULL) && (ComparePkgVersions(availPtr->version,
+		    bestPtr->version, (int *) NULL) <= 0)) {
+		continue;
+	    }
+	    if (version != NULL) {
+		result = ComparePkgVersions(availPtr->version, version,
+			&satisfies);
+		if ((result != 0) && exact) {
+		    continue;
+		}
+		if (!satisfies) {
+		    continue;
+		}
+	    }
+	    bestPtr = availPtr;
+	}
+	if (bestPtr != NULL) {
+	    /*
+	     * We found an ifneeded script for the package.  Be careful while
+	     * executing it:  this could cause reentrancy, so (a) protect the
+	     * script itself from deletion and (b) don't assume that bestPtr
+	     * will still exist when the script completes.
+	     */
+	
+	    script = bestPtr->script;
+	    Tcl_Preserve((ClientData) script);
+	    code = Tcl_GlobalEval(interp, script);
+	    Tcl_Release((ClientData) script);
+	    if (code != TCL_OK) {
+		if (code == TCL_ERROR) {
+		    Tcl_AddErrorInfo(interp,
+			    "\n    (\"package ifneeded\" script)");
+		}
+		return NULL;
+	    }
+	    Tcl_ResetResult(interp);
+	    pkgPtr = FindPackage(interp, name);
+	    break;
+	}
+
+	/*
+	 * Package not in the database.  If there is a "package unknown"
+	 * command, invoke it (but only on the first pass;  after that,
+	 * we should not get here in the first place).
+	 */
+
+	if (pass > 1) {
+	    break;
+	}
+	script = ((Interp *) interp)->packageUnknown;
+	if (script != NULL) {
+	    Tcl_DStringInit(&command);
+	    Tcl_DStringAppend(&command, script, -1);
+	    Tcl_DStringAppendElement(&command, name);
+	    Tcl_DStringAppend(&command, " ", 1);
+	    Tcl_DStringAppend(&command, (version != NULL) ? version : "{}",
+		    -1);
+	    if (exact) {
+		Tcl_DStringAppend(&command, " -exact", 7);
+	    }
+	    code = Tcl_GlobalEval(interp, Tcl_DStringValue(&command));
+	    Tcl_DStringFree(&command);
+	    if (code != TCL_OK) {
+		if (code == TCL_ERROR) {
+		    Tcl_AddErrorInfo(interp,
+			    "\n    (\"package unknown\" script)");
+		}
+		return NULL;
+	    }
+	    Tcl_ResetResult(interp);
+	}
+    }
+
+    if (pkgPtr->version == NULL) {
+	Tcl_AppendResult(interp, "can't find package ", name,
+		(char *) NULL);
+	if (version != NULL) {
+	    Tcl_AppendResult(interp, " ", version, (char *) NULL);
+	}
+	return NULL;
+    }
+
+    /*
+     * At this point we now that the package is present.  Make sure that the
+     * provided version meets the current requirement.
+     */
+
+    if (version == NULL) {
+	return pkgPtr->version;
+    }
+    result = ComparePkgVersions(pkgPtr->version, version, &satisfies);
+    if ((satisfies && !exact) || (result == 0)) {
+	return pkgPtr->version;
+    }
+    Tcl_AppendResult(interp, "version conflict for package \"",
+	    name, "\": have ", pkgPtr->version, ", need ", version,
+	    (char *) NULL);
+    return NULL;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_PackageCmd --
+ *
+ *	This procedure is invoked to process the "package" Tcl command.
+ *	See the user documentation for details on what it does.
+ *
+ * Results:
+ *	A standard Tcl result.
+ *
+ * Side effects:
+ *	See the user documentation.
+ *
+ *----------------------------------------------------------------------
+ */
+
+	/* ARGSUSED */
+int
+Tcl_PackageCmd(dummy, interp, argc, argv)
+    ClientData dummy;			/* Not used. */
+    Tcl_Interp *interp;			/* Current interpreter. */
+    int argc;				/* Number of arguments. */
+    char **argv;			/* Argument strings. */
+{
+    Interp *iPtr = (Interp *) interp;
+    size_t length;
+    int c, exact, i, satisfies;
+    PkgAvail *availPtr, *prevPtr;
+    Package *pkgPtr;
+    Tcl_HashEntry *hPtr;
+    Tcl_HashSearch search;
+    Tcl_HashTable *tablePtr;
+    char *version;
+    char buf[30];
+
+    if (argc < 2) {
+	Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
+		" option ?arg arg ...?\"", (char *) NULL);
+	return TCL_ERROR;
+    }
+    c = argv[1][0];
+    length = strlen(argv[1]);
+    if ((c == 'f') && (strncmp(argv[1], "forget", length) == 0)) {
+	for (i = 2; i < argc; i++) {
+	    hPtr = Tcl_FindHashEntry(&iPtr->packageTable, argv[i]);
+	    if (hPtr == NULL) {
+		return TCL_OK;
+	    }
+	    pkgPtr = (Package *) Tcl_GetHashValue(hPtr);
+	    Tcl_DeleteHashEntry(hPtr);
+	    if (pkgPtr->version != NULL) {
+		ckfree(pkgPtr->version);
+	    }
+	    while (pkgPtr->availPtr != NULL) {
+		availPtr = pkgPtr->availPtr;
+		pkgPtr->availPtr = availPtr->nextPtr;
+		ckfree(availPtr->version);
+		Tcl_EventuallyFree((ClientData)availPtr->script, TCL_DYNAMIC);
+		ckfree((char *) availPtr);
+	    }
+	    ckfree((char *) pkgPtr);
+	}
+    } else if ((c == 'i') && (strncmp(argv[1], "ifneeded", length) == 0)) {
+	if ((argc != 4) && (argc != 5)) {
+	    Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
+		    " ifneeded package version ?script?\"", (char *) NULL);
+	    return TCL_ERROR;
+	}
+	if (CheckVersion(interp, argv[3]) != TCL_OK) {
+	    return TCL_ERROR;
+	}
+	if (argc == 4) {
+	    hPtr = Tcl_FindHashEntry(&iPtr->packageTable, argv[2]);
+	    if (hPtr == NULL) {
+		return TCL_OK;
+	    }
+	    pkgPtr = (Package *) Tcl_GetHashValue(hPtr);
+	} else {
+	    pkgPtr = FindPackage(interp, argv[2]);
+	}
+	for (availPtr = pkgPtr->availPtr, prevPtr = NULL; availPtr != NULL;
+		prevPtr = availPtr, availPtr = availPtr->nextPtr) {
+	    if (ComparePkgVersions(availPtr->version, argv[3], (int *) NULL)
+		    == 0) {
+		if (argc == 4) {
+		    Tcl_SetResult(interp, availPtr->script, TCL_VOLATILE);
+		    return TCL_OK;
+		}
+		Tcl_EventuallyFree((ClientData)availPtr->script, TCL_DYNAMIC);
+		break;
+	    }
+	}
+	if (argc == 4) {
+	    return TCL_OK;
+	}
+	if (availPtr == NULL) {
+	    availPtr = (PkgAvail *) ckalloc(sizeof(PkgAvail));
+	    availPtr->version = ckalloc((unsigned) (strlen(argv[3]) + 1));
+	    strcpy(availPtr->version, argv[3]);
+	    if (prevPtr == NULL) {
+		availPtr->nextPtr = pkgPtr->availPtr;
+		pkgPtr->availPtr = availPtr;
+	    } else {
+		availPtr->nextPtr = prevPtr->nextPtr;
+		prevPtr->nextPtr = availPtr;
+	    }
+	}
+	availPtr->script = ckalloc((unsigned) (strlen(argv[4]) + 1));
+	strcpy(availPtr->script, argv[4]);
+    } else if ((c == 'n') && (strncmp(argv[1], "names", length) == 0)) {
+	if (argc != 2) {
+	    Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
+		    " names\"", (char *) NULL);
+	    return TCL_ERROR;
+	}
+	tablePtr = &iPtr->packageTable;
+	for (hPtr = Tcl_FirstHashEntry(tablePtr, &search); hPtr != NULL;
+		hPtr = Tcl_NextHashEntry(&search)) {
+	    pkgPtr = (Package *) Tcl_GetHashValue(hPtr);
+	    if ((pkgPtr->version != NULL) || (pkgPtr->availPtr != NULL)) {
+		Tcl_AppendElement(interp, Tcl_GetHashKey(tablePtr, hPtr));
+	    }
+	}
+    } else if ((c == 'p') && (strncmp(argv[1], "provide", length) == 0)) {
+	if ((argc != 3) && (argc != 4)) {
+	    Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
+		    " provide package ?version?\"", (char *) NULL);
+	    return TCL_ERROR;
+	}
+	if (argc == 3) {
+	    hPtr = Tcl_FindHashEntry(&iPtr->packageTable, argv[2]);
+	    if (hPtr != NULL) {
+		pkgPtr = (Package *) Tcl_GetHashValue(hPtr);
+		if (pkgPtr->version != NULL) {
+		    Tcl_SetResult(interp, pkgPtr->version, TCL_VOLATILE);
+		}
+	    }
+	    return TCL_OK;
+	}
+	if (CheckVersion(interp, argv[3]) != TCL_OK) {
+	    return TCL_ERROR;
+	}
+	return Tcl_PkgProvide(interp, argv[2], argv[3]);
+    } else if ((c == 'r') && (strncmp(argv[1], "require", length) == 0)) {
+	if (argc < 3) {
+	    requireSyntax:
+	    Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
+		    " require ?-exact? package ?version?\"", (char *) NULL);
+	    return TCL_ERROR;
+	}
+	if ((argv[2][0] == '-') && (strcmp(argv[2], "-exact") == 0)) {
+	    exact = 1;
+	} else {
+	    exact = 0;
+	}
+	version = NULL;
+	if (argc == (4+exact)) {
+	    version = argv[3+exact];
+	    if (CheckVersion(interp, version) != TCL_OK) {
+		return TCL_ERROR;
+	    }
+	} else if ((argc != 3) || exact) {
+	    goto requireSyntax;
+	}
+	version = Tcl_PkgRequire(interp, argv[2+exact], version, exact);
+	if (version == NULL) {
+	    return TCL_ERROR;
+	}
+	Tcl_SetResult(interp, version, TCL_VOLATILE);
+    } else if ((c == 'u') && (strncmp(argv[1], "unknown", length) == 0)) {
+	if (argc == 2) {
+	    if (iPtr->packageUnknown != NULL) {
+		Tcl_SetResult(interp, iPtr->packageUnknown, TCL_VOLATILE);
+	    }
+	} else if (argc == 3) {
+	    if (iPtr->packageUnknown != NULL) {
+		ckfree(iPtr->packageUnknown);
+	    }
+	    if (argv[2][0] == 0) {
+		iPtr->packageUnknown = NULL;
+	    } else {
+		iPtr->packageUnknown = (char *) ckalloc((unsigned)
+			(strlen(argv[2]) + 1));
+		strcpy(iPtr->packageUnknown, argv[2]);
+	    }
+	} else {
+	    Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
+		    " unknown ?command?\"", (char *) NULL);
+	    return TCL_ERROR;
+	}
+    } else if ((c == 'v') && (strncmp(argv[1], "vcompare", length) == 0)
+	    && (length >= 2)) {
+	if (argc != 4) {
+	    Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
+		    " vcompare version1 version2\"", (char *) NULL);
+	    return TCL_ERROR;
+	}
+	if ((CheckVersion(interp, argv[2]) != TCL_OK)
+		|| (CheckVersion(interp, argv[3]) != TCL_OK)) {
+	    return TCL_ERROR;
+	}
+	TclFormatInt(buf, ComparePkgVersions(argv[2], argv[3], (int *) NULL));
+	Tcl_SetResult(interp, buf, TCL_VOLATILE);
+    } else if ((c == 'v') && (strncmp(argv[1], "versions", length) == 0)
+	    && (length >= 2)) {
+	if (argc != 3) {
+	    Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
+		    " versions package\"", (char *) NULL);
+	    return TCL_ERROR;
+	}
+	hPtr = Tcl_FindHashEntry(&iPtr->packageTable, argv[2]);
+	if (hPtr != NULL) {
+	    pkgPtr = (Package *) Tcl_GetHashValue(hPtr);
+	    for (availPtr = pkgPtr->availPtr; availPtr != NULL;
+		    availPtr = availPtr->nextPtr) {
+		Tcl_AppendElement(interp, availPtr->version);
+	    }
+	}
+    } else if ((c == 'v') && (strncmp(argv[1], "vsatisfies", length) == 0)
+	    && (length >= 2)) {
+	if (argc != 4) {
+	    Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
+		    " vsatisfies version1 version2\"", (char *) NULL);
+	    return TCL_ERROR;
+	}
+	if ((CheckVersion(interp, argv[2]) != TCL_OK)
+		|| (CheckVersion(interp, argv[3]) != TCL_OK)) {
+	    return TCL_ERROR;
+	}
+	ComparePkgVersions(argv[2], argv[3], &satisfies);
+	TclFormatInt(buf, satisfies);
+	Tcl_SetResult(interp, buf, TCL_VOLATILE);
+    } else {
+	Tcl_AppendResult(interp, "bad option \"", argv[1],
+		"\": should be forget, ifneeded, names, ",
+		"provide, require, unknown, vcompare, ",
+		"versions, or vsatisfies", (char *) NULL);
+	return TCL_ERROR;
+    }
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * FindPackage --
+ *
+ *	This procedure finds the Package record for a particular package
+ *	in a particular interpreter, creating a record if one doesn't
+ *	already exist.
+ *
+ * Results:
+ *	The return value is a pointer to the Package record for the
+ *	package.
+ *
+ * Side effects:
+ *	A new Package record may be created.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static Package *
+FindPackage(interp, name)
+    Tcl_Interp *interp;		/* Interpreter to use for package lookup. */
+    char *name;			/* Name of package to fine. */
+{
+    Interp *iPtr = (Interp *) interp;
+    Tcl_HashEntry *hPtr;
+    int new;
+    Package *pkgPtr;
+
+    hPtr = Tcl_CreateHashEntry(&iPtr->packageTable, name, &new);
+    if (new) {
+	pkgPtr = (Package *) ckalloc(sizeof(Package));
+	pkgPtr->version = NULL;
+	pkgPtr->availPtr = NULL;
+	Tcl_SetHashValue(hPtr, pkgPtr);
+    } else {
+	pkgPtr = (Package *) Tcl_GetHashValue(hPtr);
+    }
+    return pkgPtr;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclFreePackageInfo --
+ *
+ *	This procedure is called during interpreter deletion to
+ *	free all of the package-related information for the
+ *	interpreter.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Memory is freed.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void
+TclFreePackageInfo(iPtr)
+    Interp *iPtr;		/* Interpereter that is being deleted. */
+{
+    Package *pkgPtr;
+    Tcl_HashSearch search;
+    Tcl_HashEntry *hPtr;
+    PkgAvail *availPtr;
+
+    for (hPtr = Tcl_FirstHashEntry(&iPtr->packageTable, &search);
+	    hPtr != NULL;  hPtr = Tcl_NextHashEntry(&search)) {
+	pkgPtr = (Package *) Tcl_GetHashValue(hPtr);
+	if (pkgPtr->version != NULL) {
+	    ckfree(pkgPtr->version);
+	}
+	while (pkgPtr->availPtr != NULL) {
+	    availPtr = pkgPtr->availPtr;
+	    pkgPtr->availPtr = availPtr->nextPtr;
+	    ckfree(availPtr->version);
+	    Tcl_EventuallyFree((ClientData)availPtr->script, TCL_DYNAMIC);
+	    ckfree((char *) availPtr);
+	}
+	ckfree((char *) pkgPtr);
+    }
+    Tcl_DeleteHashTable(&iPtr->packageTable);
+    if (iPtr->packageUnknown != NULL) {
+	ckfree(iPtr->packageUnknown);
+    }
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * CheckVersion --
+ *
+ *	This procedure checks to see whether a version number has
+ *	valid syntax.
+ *
+ * Results:
+ *	If string is a properly formed version number the TCL_OK
+ *	is returned.  Otherwise TCL_ERROR is returned and an error
+ *	message is left in interp->result.
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+CheckVersion(interp, string)
+    Tcl_Interp *interp;		/* Used for error reporting. */
+    char *string;		/* Supposedly a version number, which is
+				 * groups of decimal digits separated
+				 * by dots. */
+{
+    char *p = string;
+
+    if (!isdigit(UCHAR(*p))) {
+	goto error;
+    }
+    for (p++; *p != 0; p++) {
+	if (!isdigit(UCHAR(*p)) && (*p != '.')) {
+	    goto error;
+	}
+    }
+    if (p[-1] != '.') {
+	return TCL_OK;
+    }
+
+    error:
+    Tcl_AppendResult(interp, "expected version number but got \"",
+	    string, "\"", (char *) NULL);
+    return TCL_ERROR;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * ComparePkgVersions --
+ *
+ *	This procedure compares two version numbers.
+ *
+ * Results:
+ *	The return value is -1 if v1 is less than v2, 0 if the two
+ *	version numbers are the same, and 1 if v1 is greater than v2.
+ *	If *satPtr is non-NULL, the word it points to is filled in
+ *	with 1 if v2 >= v1 and both numbers have the same major number
+ *	or 0 otherwise.
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+ComparePkgVersions(v1, v2, satPtr)
+    char *v1, *v2;		/* Versions strings, of form 2.1.3 (any
+				 * number of version numbers). */
+    int *satPtr;		/* If non-null, the word pointed to is
+				 * filled in with a 0/1 value.  1 means
+				 * v1 "satisfies" v2:  v1 is greater than
+				 * or equal to v2 and both version numbers
+				 * have the same major number. */
+{
+    int thisIsMajor, n1, n2;
+
+    /*
+     * Each iteration of the following loop processes one number from
+     * each string, terminated by a ".".  If those numbers don't match
+     * then the comparison is over;  otherwise, we loop back for the
+     * next number.
+     */
+
+    thisIsMajor = 1;
+    while (1) {
+	/*
+	 * Parse one decimal number from the front of each string.
+	 */
+
+	n1 = n2 = 0;
+	while ((*v1 != 0) && (*v1 != '.')) {
+	    n1 = 10*n1 + (*v1 - '0');
+	    v1++;
+	}
+	while ((*v2 != 0) && (*v2 != '.')) {
+	    n2 = 10*n2 + (*v2 - '0');
+	    v2++;
+	}
+
+	/*
+	 * Compare and go on to the next version number if the
+	 * current numbers match.
+	 */
+
+	if (n1 != n2) {
+	    break;
+	}
+	if (*v1 != 0) {
+	    v1++;
+	} else if (*v2 == 0) {
+	    break;
+	}
+	if (*v2 != 0) {
+	    v2++;
+	}
+	thisIsMajor = 0;
+    }
+    if (satPtr != NULL) {
+	*satPtr = (n1 == n2) || ((n1 > n2) && !thisIsMajor);
+    }
+    if (n1 > n2) {
+	return 1;
+    } else if (n1 == n2) {
+	return 0;
+    } else {
+	return -1;
+    }
+}