libvmcp: Add common vmcp code to the lib

This patch prevents code duplication in vmcp related programs.
Some applications such as vmur, vmcp, and lsqeth
use z/VM CP commands to query information. Each program
uses its own defines and code.

Supply a library and common header file to use common code.

Signed-off-by: Thomas Richter <tmricht@linux.vnet.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Reviewed-by: Jan Höppner <hoeppner@linux.vnet.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>

.gitignore

@@ -46,6 +46,7 @@ libutil/util_prg_example
 libutil/util_rec_example
 libutil/util_scandir_example
 libzds/libzds.a
+libvmcp/vmcp_example
 mon_tools/mon_fsstatd
 mon_tools/mon_procd
 osasnmpd/osasnmpd

Makefile

@@ -3,7 +3,7 @@ ARCH := $(shell uname -m | sed -e s/i.86/i386/ -e s/sun4u/sparc64/ -e s/arm.*/ar
 # Include common definitions
 include common.mak
 
-LIB_DIRS = libvtoc libu2s libutil libzds libdasd libvmdump libccw
+LIB_DIRS = libvtoc libu2s libutil libzds libdasd libvmdump libccw libvmcp
 TOOL_DIRS = zipl zdump fdasd dasdfmt dasdview tunedasd \
 	   tape390 osasnmpd qetharp ip_watcher qethconf scripts zconf \
 	   vmconvert vmcp man mon_tools dasdinfo vmur cpuplugd ipl_tools \

common.mak

@@ -338,6 +338,10 @@ $(rootdir)/libvmdump/libvmdump.a: $(rootdir)/libvmdump
 	$(MAKE) -C $(rootdir)/libvmdump/ libvmdump.a
 .PHONY: $(rootdir)/libvmdump
 
+$(rootdir)/libvmcp/libvmcp.a: $(rootdir)/libvmcp
+	$(MAKE) -C $(rootdir)/libvmcp/ libvmcp.a
+.PHONY: $(rootdir)/libvmcp
+
 $(rootdir)/zipl/boot/data.o:
 	$(MAKE) -C $(rootdir)/zipl/boot/ data.o
 

include/lib/vmcp.h

@@ -0,0 +1,52 @@
+/*
+ * vmcp - z/VM CP command library
+ *
+ * Copyright IBM Corp. 2005, 2018
+ *
+ * s390-tools is free software; you can redistribute it and/or modify
+ * it under the terms of the MIT license. See LICENSE for details.
+ */
+
+#ifndef LIB_VMCP_H
+#define LIB_VMCP_H
+
+#include <stdbool.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define	VMCP_DEVICE_NODE	"/dev/vmcp"	/* VMCP device name */
+#define	VMCP_DEFAULT_BUFSZ	0x4000		/* VMCP default buffer size */
+
+/*
+ * Error codes returned by vmcp() function. This enables the caller
+ * to emit a detailed error message on the type of failure.
+ */
+#define	VMCP_SUCCESS	0	/* VMCP operation completed successfully */
+#define	VMCP_ERR_OPEN		(-1)	/* Error Open of VMCP device */
+#define	VMCP_ERR_SETBUF		(-2)	/* Error VMCP_SETBUF ioctl */
+#define	VMCP_ERR_READ		(-3)	/* Error VMCP read system call */
+#define	VMCP_ERR_GETCODE	(-4)	/* Error VMCP_GETCODE ioctl */
+#define	VMCP_ERR_GETSIZE	(-5)	/* Error VMCP_GETSIZE ioctl */
+#define	VMCP_ERR_TOOSMALL	(-6)	/* Error VMCP buffer too small for
+					 * response
+					 */
+#define	VMCP_ERR_WRITE		(-7)	/* Error VMCP write system call */
+
+struct vmcp_parm {
+	const char *cpcmd;
+	unsigned int buffer_size;
+	bool do_upper;
+	int cprc;
+	char *response;
+	unsigned int response_size;
+};
+
+int vmcp(struct vmcp_parm *cp);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

libvmcp/Makefile

@@ -0,0 +1,18 @@
+include ../common.mak
+
+lib = libvmcp.a
+
+examples = vmcp_example
+
+all: $(lib) $(examples)
+
+objects = vmcp.o
+
+$(lib): $(objects)
+
+install: all
+
+vmcp_example: vmcp_example.o $(lib) $(rootdir)/libutil/libutil.a
+
+clean:
+	rm -f *.o $(lib) $(examples)

libvmcp/vmcp.c

@@ -0,0 +1,134 @@
+/*
+ * vmcp - z/VM CP function library
+ *
+ * Copyright IBM Corp. 2018
+ *
+ * s390-tools is free software; you can redistribute it and/or modify
+ * it under the terms of the MIT license. See LICENSE for details.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <sys/ioctl.h>
+
+#include "lib/util_libc.h"
+#include "lib/vmcp.h"
+
+#define	VMCP_DEVICE_NODE	"/dev/vmcp"
+#define	VMCP_GETSIZE		_IOR(0x10, 3, int)
+#define	VMCP_SETBUF		_IOW(0x10, 2, int)
+#define	VMCP_GETCODE		_IOR(0x10, 1, int)
+
+/*
+ * Read at most COUNT bytes from FD into memory at location BUF.
+ * Return number of bytes read on success, -1 on error.
+ */
+static ssize_t read_buffer(int fd, char *buf, ssize_t count)
+{
+	ssize_t ret, done;
+
+	for (done = 0; done < (ssize_t)count; done += ret) {
+		ret = read(fd, &buf[done], count - done);
+		if (ret == -1 && errno == EINTR)
+			continue;
+		if (ret == -1)
+			return -1;
+		if (ret == 0)
+			break;
+	}
+	return done;
+}
+
+/**
+ * Submit a command to z/VM CP and return the response, the size in bytes
+ * of the response and CP command response code.
+ *
+ * The member response contains the response from CP. It is a pointer
+ * to a malloc'ed buffer which must be freed by the caller when the return
+ * code is zero or VMCP_ERR_TOOSMALL.
+ *
+ * @param[in,out] cmd		Pointer to struct vmcp_parm.
+ * @param[in] cpcmd		Pointer to CP command string.
+ * @param[in] do_upper		If true convert cpcmd string to upper case.
+ * @param[out] cprc		Return code of the CP command.
+ * @param[out] response		Return buffer, has been allocated via malloc()
+ *				must be freed by caller, see below.
+ * @param[out] response_size	Size of the response in bytes, can be larger
+ *				than buffer_size.
+ *
+ * @returns	Zero on success or a negative error number on failure.
+ * @retval VMCP_SUCCESS		Success valid members: cprc, response,
+ *				response_size
+ * @retval VMCP_ERR_OPEN	Error opening VMCP device, valid members: none
+ * @retval VMCP_ERR_SETBUF	Error setting buffer, valid members: none
+ * @retval VMCP_ERR_GETCODE	Error getting cp exit code, valid members: none
+ * @retval VMCP_ERR_WRITE	Error write CP command, valid members: none
+ * @retval VMCP_ERR_GETSIZE	Error reading response size,
+ *				valid members: cprc
+ * @retval VMCP_ERR_READ	Error reading resp
+ * @retval VMCP_ERR_TOOSMALL	Error response buffer too small, response
+ *				truncated, valid members: cprc, response,
+ *				response_size
+ */
+int vmcp(struct vmcp_parm *cmd)
+{
+	int rc = VMCP_SUCCESS, fd, len;
+	char *cpcmd;
+
+	cmd->response = NULL;
+	cmd->response_size = 0;
+	cmd->cprc = 0;
+
+	fd = open(VMCP_DEVICE_NODE, O_RDWR);
+	if (fd == -1)
+		return VMCP_ERR_OPEN;
+
+	cpcmd = util_strdup(cmd->cpcmd);	/* Exits on failure */
+	if (cmd->do_upper)
+		util_str_toupper(cpcmd);
+
+	if (ioctl(fd, VMCP_SETBUF, &cmd->buffer_size) == -1) {
+		rc = VMCP_ERR_SETBUF;
+		goto fail;
+	}
+
+	if (write(fd, cpcmd, strlen(cpcmd)) == -1) {
+		rc = VMCP_ERR_WRITE;
+		goto fail;
+	}
+
+	if (ioctl(fd, VMCP_GETCODE, &cmd->cprc) == -1) {
+		rc = VMCP_ERR_GETCODE;
+		goto fail;
+	}
+
+	if (ioctl(fd, VMCP_GETSIZE, &cmd->response_size) == -1) {
+		rc = VMCP_ERR_GETSIZE;
+		goto fail;
+	}
+
+	if (cmd->response_size <= cmd->buffer_size) {
+		len = cmd->response_size;
+	} else {
+		len = cmd->buffer_size;
+		rc = VMCP_ERR_TOOSMALL;
+	}
+
+	/* Exits on failure */
+	cmd->response = (char *)util_zalloc(len + 1);
+
+	if (read_buffer(fd, cmd->response, len) == -1) {
+		rc = VMCP_ERR_READ;
+		free(cmd->response);
+		cmd->response = NULL;
+	}
+
+fail:
+	close(fd);
+	free(cpcmd);
+	return rc;
+}

libvmcp/vmcp_example.c

@@ -0,0 +1,65 @@
+/**
+ * vmcp_example - Example program for vmcp.c
+ *
+ * Copyright 2018 IBM Corp.
+ *
+ * s390-tools is free software; you can redistribute it and/or modify
+ * it under the terms of the MIT license. See LICENSE for details.
+ */
+
+//! [code]
+#include <stdio.h>
+#include <stdlib.h>
+#include <err.h>
+
+#include "lib/vmcp.h"
+
+/*
+ * Demonstrate vmcp() function usage
+ */
+int main(void)
+{
+	struct vmcp_parm cp;
+	int rc;
+
+	cp.cpcmd = "q osa";
+	cp.buffer_size = VMCP_DEFAULT_BUFSZ;
+	cp.do_upper = true;
+
+	rc = vmcp(&cp);
+
+	switch (rc) {
+	case VMCP_SUCCESS:
+		printf("%s\n", cp.response);
+		free(cp.response);
+		break;
+	case VMCP_ERR_OPEN:
+		errx(EXIT_FAILURE, "Could not open device %s", VMCP_DEVICE_NODE);
+		break;
+	case VMCP_ERR_SETBUF:
+		errx(EXIT_FAILURE, "Could not set buffer size");
+		break;
+	case VMCP_ERR_GETCODE:
+		errx(EXIT_FAILURE, "Could not query return code");
+		break;
+	case VMCP_ERR_GETSIZE:
+		errx(EXIT_FAILURE, "Could not query response size");
+		break;
+	case VMCP_ERR_WRITE:
+		errx(EXIT_FAILURE, "Could not issue CP command");
+		break;
+	case VMCP_ERR_READ:
+		errx(EXIT_FAILURE, "Could not read CP response");
+		break;
+	case VMCP_ERR_TOOSMALL:
+		free(cp.response);
+		printf("Response truncated (requires %u bytes)\n",
+		       cp.response_size);
+		errx(EXIT_FAILURE, "Response buffer (%u bytes) too small",
+		     cp.buffer_size);
+		break;
+	}
+	return EXIT_SUCCESS;
+}
+
+//! [code]