created lib-app skeleton (foss21.org lib-app model).

12 files changed, 997 insertions, 0 deletions

diff --git a/src/driver/tpax_amain.c b/src/driver/tpax_amain.c
new file mode 100644
index 0000000..f71f16c
--- /dev/null
+++ b/src/driver/tpax_amain.c
@@ -0,0 +1,94 @@
+/******************************************************/
+/*  tpax: a topological pax implementation            */
+/*  Copyright (C) 2020  Z. Gilboa                     */
+/*  Released under GPLv2 and GPLv3; see COPYING.TPAX. */
+/******************************************************/
+
+#include <stdio.h>
+#include <unistd.h>
+#include <tpax/tpax.h>
+#include "tpax_driver_impl.h"
+#include "tpax_dprintf_impl.h"
+
+#ifndef TPAX_DRIVER_FLAGS
+#define TPAX_DRIVER_FLAGS	TPAX_DRIVER_VERBOSITY_ERRORS \
+				| TPAX_DRIVER_VERBOSITY_USAGE
+#endif
+
+static const char vermsg[] = "%s%s%s (https://git.foss21.org/tpax): "
+			     "version %s%d.%d.%d%s.\n"
+			     "[commit reference: %s%s%s]\n";
+
+static const char * const tpax_ver_color[6] = {
+		"\x1b[1m\x1b[35m","\x1b[0m",
+		"\x1b[1m\x1b[32m","\x1b[0m",
+		"\x1b[1m\x1b[34m","\x1b[0m"
+};
+
+static const char * const tpax_ver_plain[6] = {
+		"","",
+		"","",
+		"",""
+};
+
+static ssize_t tpax_version(struct tpax_driver_ctx * dctx, int fdout)
+{
+	const struct tpax_source_version * verinfo;
+	const char * const * verclr;
+
+	verinfo = tpax_source_version();
+	verclr  = isatty(fdout) ? tpax_ver_color : tpax_ver_plain;
+
+	return tpax_dprintf(
+			fdout,vermsg,
+			verclr[0],dctx->program,verclr[1],
+			verclr[2],verinfo->major,verinfo->minor,
+			verinfo->revision,verclr[3],
+			verclr[4],verinfo->commit,verclr[5]);
+}
+
+static void tpax_perform_unit_actions(
+	const struct tpax_driver_ctx *	dctx,
+	struct tpax_unit_ctx *		uctx)
+{
+	(void)dctx;
+	(void)uctx;
+}
+
+static int tpax_exit(struct tpax_driver_ctx * dctx, int ret)
+{
+	tpax_output_error_vector(dctx);
+	tpax_free_driver_ctx(dctx);
+	return ret;
+}
+
+int tpax_main(char ** argv, char ** envp, const struct tpax_fd_ctx * fdctx)
+{
+	int			ret;
+	int			fdout;
+	uint64_t		flags;
+	struct tpax_driver_ctx *	dctx;
+	struct tpax_unit_ctx *	uctx;
+	const char **		unit;
+
+	flags = TPAX_DRIVER_FLAGS;
+	fdout = fdctx ? fdctx->fdout : STDOUT_FILENO;
+
+	if ((ret = tpax_get_driver_ctx(argv,envp,flags,fdctx,&dctx)))
+		return (ret == TPAX_USAGE)
+			? !argv || !argv[0] || !argv[1]
+			: TPAX_ERROR;
+
+	if (dctx->cctx->drvflags & TPAX_DRIVER_VERSION)
+		if ((tpax_version(dctx,fdout)) < 0)
+			return tpax_exit(dctx,TPAX_ERROR);
+
+	for (unit=dctx->units; *unit; unit++) {
+		if (!(tpax_get_unit_ctx(dctx,*unit,&uctx))) {
+			tpax_perform_unit_actions(dctx,uctx);
+			tpax_free_unit_ctx(uctx);
+		}
+	}
+
+	return tpax_exit(dctx,dctx->errv[0] ? TPAX_ERROR : TPAX_OK);
+}
diff --git a/src/driver/tpax_driver_ctx.c b/src/driver/tpax_driver_ctx.c
new file mode 100644
index 0000000..96fe8ff
--- /dev/null
+++ b/src/driver/tpax_driver_ctx.c
@@ -0,0 +1,248 @@
+/******************************************************/
+/*  tpax: a topological pax implementation            */
+/*  Copyright (C) 2020  Z. Gilboa                     */
+/*  Released under GPLv2 and GPLv3; see COPYING.TPAX. */
+/******************************************************/
+
+#include <stdint.h>
+#include <unistd.h>
+#include <fcntl.h>
+
+#define ARGV_DRIVER
+
+#include <tpax/tpax.h>
+#include "tpax_version.h"
+#include "tpax_driver_impl.h"
+#include "argv/argv.h"
+
+/* package info */
+static const struct tpax_source_version tpax_src_version = {
+	TPAX_TAG_VER_MAJOR,
+	TPAX_TAG_VER_MINOR,
+	TPAX_TAG_VER_PATCH,
+	TPAX_GIT_VERSION
+};
+
+/* default fd context */
+static const struct tpax_fd_ctx tpax_default_fdctx = {
+	.fdin  = STDIN_FILENO,
+	.fdout = STDOUT_FILENO,
+	.fderr = STDERR_FILENO,
+	.fdcwd = AT_FDCWD,
+	.fddst = AT_FDCWD,
+	.fdlog = (-1),
+};
+
+struct tpax_driver_ctx_alloc {
+	struct argv_meta *		meta;
+	struct tpax_driver_ctx_impl	ctx;
+	uint64_t			guard;
+	const char *			units[];
+};
+
+static uint32_t tpax_argv_flags(uint32_t flags)
+{
+	uint32_t ret = ARGV_CLONE_VECTOR;
+
+	if (flags & TPAX_DRIVER_VERBOSITY_NONE)
+		ret |= ARGV_VERBOSITY_NONE;
+
+	if (flags & TPAX_DRIVER_VERBOSITY_ERRORS)
+		ret |= ARGV_VERBOSITY_ERRORS;
+
+	if (flags & TPAX_DRIVER_VERBOSITY_STATUS)
+		ret |= ARGV_VERBOSITY_STATUS;
+
+	return ret;
+}
+
+static int tpax_driver_usage(
+	int				fdout,
+	const char *			program,
+	const char *			arg,
+	const struct argv_option **	optv,
+	struct argv_meta *		meta)
+{
+	char header[512];
+
+	snprintf(header,sizeof(header),
+		"Usage: %s [options] <file>...\n" "Options:\n",
+		program);
+
+	argv_usage(fdout,header,optv,arg);
+	argv_free(meta);
+
+	return TPAX_USAGE;
+}
+
+static struct tpax_driver_ctx_impl * tpax_driver_ctx_alloc(
+	struct argv_meta *		meta,
+	const struct tpax_fd_ctx *	fdctx,
+	const struct tpax_common_ctx *	cctx,
+	size_t				nunits)
+{
+	struct tpax_driver_ctx_alloc *	ictx;
+	size_t				size;
+	struct argv_entry *		entry;
+	const char **			units;
+	int				elements;
+
+	size =  sizeof(struct tpax_driver_ctx_alloc);
+	size += (nunits+1)*sizeof(const char *);
+
+	if (!(ictx = calloc(1,size)))
+		return 0;
+
+	memcpy(&ictx->ctx.fdctx,fdctx,sizeof(*fdctx));
+	memcpy(&ictx->ctx.cctx,cctx,sizeof(*cctx));
+
+	elements = sizeof(ictx->ctx.erribuf) / sizeof(*ictx->ctx.erribuf);
+
+	ictx->ctx.errinfp  = &ictx->ctx.erriptr[0];
+	ictx->ctx.erricap  = &ictx->ctx.erriptr[--elements];
+
+	ictx->meta = meta;
+
+	for (entry=meta->entries,units=ictx->units; entry->fopt || entry->arg; entry++)
+		if (!entry->fopt)
+			*units++ = entry->arg;
+
+	ictx->ctx.ctx.units = ictx->units;
+	ictx->ctx.ctx.errv  = ictx->ctx.errinfp;
+	return &ictx->ctx;
+}
+
+static int tpax_get_driver_ctx_fail(struct argv_meta * meta)
+{
+	argv_free(meta);
+	return -1;
+}
+
+int tpax_get_driver_ctx(
+	char **				argv,
+	char **				envp,
+	uint32_t			flags,
+	const struct tpax_fd_ctx *	fdctx,
+	struct tpax_driver_ctx ** 	pctx)
+{
+	struct tpax_driver_ctx_impl *	ctx;
+	struct tpax_common_ctx		cctx;
+	const struct argv_option *	optv[TPAX_OPTV_ELEMENTS];
+	struct argv_meta *		meta;
+	struct argv_entry *		entry;
+	size_t				nunits;
+	const char *			program;
+
+	(void)envp;
+
+	if (!fdctx)
+		fdctx = &tpax_default_fdctx;
+
+	argv_optv_init(tpax_default_options,optv);
+
+	if (!(meta = argv_get(
+			argv,optv,
+			tpax_argv_flags(flags),
+			fdctx->fderr)))
+		return -1;
+
+	nunits	= 0;
+	program = argv_program_name(argv[0]);
+	memset(&cctx,0,sizeof(cctx));
+	cctx.drvflags = flags;
+
+	if (!argv[1] && (flags & TPAX_DRIVER_VERBOSITY_USAGE))
+		return tpax_driver_usage(
+			fdctx->fderr,
+			program,
+			0,optv,meta);
+
+	/* get options, count units */
+	for (entry=meta->entries; entry->fopt || entry->arg; entry++) {
+		if (entry->fopt) {
+			switch (entry->tag) {
+				case TAG_HELP:
+					if (flags & TPAX_DRIVER_VERBOSITY_USAGE)
+						return tpax_driver_usage(
+							fdctx->fdout,
+							program,entry->arg,
+							optv,meta);
+					break;
+
+				case TAG_VERSION:
+					cctx.drvflags |= TPAX_DRIVER_VERSION;
+					break;
+			}
+		} else
+			nunits++;
+	}
+
+	if (!(ctx = tpax_driver_ctx_alloc(meta,fdctx,&cctx,nunits)))
+		return tpax_get_driver_ctx_fail(meta);
+
+	ctx->ctx.program	= program;
+	ctx->ctx.cctx		= &ctx->cctx;
+
+	*pctx = &ctx->ctx;
+	return TPAX_OK;
+}
+
+static void tpax_free_driver_ctx_impl(struct tpax_driver_ctx_alloc * ictx)
+{
+	argv_free(ictx->meta);
+	free(ictx);
+}
+
+void tpax_free_driver_ctx(struct tpax_driver_ctx * ctx)
+{
+	struct tpax_driver_ctx_alloc *	ictx;
+	uintptr_t			addr;
+
+	if (ctx) {
+		addr = (uintptr_t)ctx - offsetof(struct tpax_driver_ctx_impl,ctx);
+		addr = addr - offsetof(struct tpax_driver_ctx_alloc,ctx);
+		ictx = (struct tpax_driver_ctx_alloc *)addr;
+		tpax_free_driver_ctx_impl(ictx);
+	}
+}
+
+const struct tpax_source_version * tpax_source_version(void)
+{
+	return &tpax_src_version;
+}
+
+int tpax_get_driver_fdctx(
+	const struct tpax_driver_ctx *	dctx,
+	struct tpax_fd_ctx *		fdctx)
+{
+	struct tpax_driver_ctx_impl *	ictx;
+
+	ictx = tpax_get_driver_ictx(dctx);
+
+	fdctx->fdin  = ictx->fdctx.fdin;
+	fdctx->fdout = ictx->fdctx.fdout;
+	fdctx->fderr = ictx->fdctx.fderr;
+	fdctx->fdlog = ictx->fdctx.fdlog;
+	fdctx->fdcwd = ictx->fdctx.fdcwd;
+	fdctx->fddst = ictx->fdctx.fddst;
+
+	return 0;
+}
+
+int tpax_set_driver_fdctx(
+	struct tpax_driver_ctx *	dctx,
+	const struct tpax_fd_ctx *	fdctx)
+{
+	struct tpax_driver_ctx_impl *	ictx;
+
+	ictx = tpax_get_driver_ictx(dctx);
+
+	ictx->fdctx.fdin  = fdctx->fdin;
+	ictx->fdctx.fdout = fdctx->fdout;
+	ictx->fdctx.fderr = fdctx->fderr;
+	ictx->fdctx.fdlog = fdctx->fdlog;
+	ictx->fdctx.fdcwd = fdctx->fdcwd;
+	ictx->fdctx.fddst = fdctx->fddst;
+
+	return 0;
+}
diff --git a/src/driver/tpax_unit_ctx.c b/src/driver/tpax_unit_ctx.c
new file mode 100644
index 0000000..a6a91b6
--- /dev/null
+++ b/src/driver/tpax_unit_ctx.c
@@ -0,0 +1,61 @@
+/******************************************************/
+/*  tpax: a topological pax implementation            */
+/*  Copyright (C) 2020  Z. Gilboa                     */
+/*  Released under GPLv2 and GPLv3; see COPYING.TPAX. */
+/******************************************************/
+
+#include <stdint.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+
+#include <tpax/tpax.h>
+#include "tpax_driver_impl.h"
+#include "tpax_errinfo_impl.h"
+
+static int tpax_free_unit_ctx_impl(struct tpax_unit_ctx_impl * ctx, int ret)
+{
+	if (ctx) {
+		free(ctx);
+	}
+
+	return ret;
+}
+
+int tpax_get_unit_ctx(
+	const struct tpax_driver_ctx *	dctx,
+	const char *			path,
+	struct tpax_unit_ctx **		pctx)
+{
+	struct tpax_unit_ctx_impl *	ctx;
+
+	if (!dctx)
+		return TPAX_CUSTOM_ERROR(
+			dctx,TPAX_ERR_NULL_CONTEXT);
+
+	else if (!(ctx = calloc(1,sizeof(*ctx))))
+		return TPAX_BUFFER_ERROR(dctx);
+
+	tpax_driver_set_ectx(
+		dctx,0,path);
+
+	ctx->path	= path;
+	ctx->uctx.path	= &ctx->path;
+
+	*pctx = &ctx->uctx;
+
+	return 0;
+}
+
+void tpax_free_unit_ctx(struct tpax_unit_ctx * ctx)
+{
+	struct tpax_unit_ctx_impl *	ictx;
+	uintptr_t			addr;
+
+	if (ctx) {
+		addr = (uintptr_t)ctx - offsetof(struct tpax_unit_ctx_impl,uctx);
+		ictx = (struct tpax_unit_ctx_impl *)addr;
+		tpax_free_unit_ctx_impl(ictx,0);
+	}
+}
diff --git a/src/internal/tpax_dprintf_impl.c b/src/internal/tpax_dprintf_impl.c
new file mode 100644
index 0000000..5d2f5f8
--- /dev/null
+++ b/src/internal/tpax_dprintf_impl.c
@@ -0,0 +1,62 @@
+/******************************************************/
+/*  tpax: a topological pax implementation            */
+/*  Copyright (C) 2020  Z. Gilboa                     */
+/*  Released under GPLv2 and GPLv3; see COPYING.TPAX. */
+/******************************************************/
+
+#include <stdio.h>
+#include <stdarg.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+
+int tpax_dprintf(int fd, const char * fmt, ...)
+{
+	int	ret;
+	int	cnt;
+	int	size;
+	va_list	ap;
+	char *	ch;
+	char *	buf;
+	char	chbuf[2048];
+
+	va_start(ap,fmt);
+
+	size = sizeof(chbuf);
+	buf  = ((cnt = vsnprintf(chbuf,size,fmt,ap)) < size)
+		? chbuf : malloc(cnt + 1);
+
+	va_end(ap);
+
+	if (buf == chbuf) {
+		(void)0;
+
+	} else if (buf) {
+		va_start(ap,fmt);
+		vsprintf(buf,fmt,ap);
+		va_end(ap);
+
+	} else {
+		return -1;
+	}
+
+	ret = 0;
+	ch  = buf;
+
+	for (; cnt && ret>=0; ) {
+		ret = write(fd,ch,cnt);
+
+		while ((ret < 0) && (errno == EINTR))
+			ret = write(fd,ch,cnt);
+
+		ch  += ret;
+		cnt -= ret;
+	}
+
+	ret = (ret < 0) ? -1 : ch - buf;
+
+	if (buf != chbuf)
+		free(buf);
+
+	return ret;
+}
diff --git a/src/internal/tpax_dprintf_impl.h b/src/internal/tpax_dprintf_impl.h
new file mode 100644
index 0000000..d83d0d3
--- /dev/null
+++ b/src/internal/tpax_dprintf_impl.h
@@ -0,0 +1,10 @@
+#ifndef TPAX_DPRINTF_IMPL_H
+#define TPAX_DPRINTF_IMPL_H
+
+#ifdef  ARGV_DRIVER
+#define argv_dprintf tpax_dprintf
+#endif
+
+int tpax_dprintf(int fd, const char * fmt, ...);
+
+#endif
diff --git a/src/internal/tpax_driver_impl.h b/src/internal/tpax_driver_impl.h
new file mode 100644
index 0000000..49dea15
--- /dev/null
+++ b/src/internal/tpax_driver_impl.h
@@ -0,0 +1,112 @@
+/******************************************************/
+/*  tpax: a topological pax implementation            */
+/*  Copyright (C) 2020  Z. Gilboa                     */
+/*  Released under GPLv2 and GPLv3; see COPYING.TPAX. */
+/******************************************************/
+
+#ifndef TPAX_DRIVER_IMPL_H
+#define TPAX_DRIVER_IMPL_H
+
+#include <stdint.h>
+#include <stdio.h>
+#include <sys/types.h>
+
+#include <tpax/tpax.h>
+#include "tpax_dprintf_impl.h"
+#include "argv/argv.h"
+
+#define TPAX_OPTV_ELEMENTS 64
+
+extern const struct argv_option tpax_default_options[];
+
+enum app_tags {
+	TAG_HELP,
+	TAG_VERSION,
+};
+
+struct tpax_driver_ctx_impl {
+	struct tpax_common_ctx        cctx;
+	struct tpax_driver_ctx        ctx;
+	struct tpax_fd_ctx            fdctx;
+	const struct tpax_unit_ctx *  euctx;
+	const char *                  eunit;
+	struct tpax_error_info **     errinfp;
+	struct tpax_error_info **     erricap;
+	struct tpax_error_info *      erriptr[64];
+	struct tpax_error_info        erribuf[64];
+};
+
+struct tpax_unit_ctx_impl {
+	const char *		path;
+	struct tpax_unit_ctx	uctx;
+};
+
+
+static inline struct tpax_driver_ctx_impl * tpax_get_driver_ictx(
+	const struct tpax_driver_ctx * dctx)
+{
+        uintptr_t addr;
+
+        if (dctx) {
+                addr = (uintptr_t)dctx - offsetof(struct tpax_driver_ctx_impl,ctx);
+                return (struct tpax_driver_ctx_impl *)addr;
+        }
+
+        return 0;
+}
+
+static inline void tpax_driver_set_ectx(
+	const struct tpax_driver_ctx * dctx,
+	const struct tpax_unit_ctx *   uctx,
+	const char *                 unit)
+{
+	struct tpax_driver_ctx_impl *  ictx;
+
+	ictx        = tpax_get_driver_ictx(dctx);
+	ictx->euctx = uctx;
+	ictx->eunit = unit;
+}
+
+static inline int tpax_driver_fdin(const struct tpax_driver_ctx * dctx)
+{
+	struct tpax_fd_ctx fdctx;
+	tpax_get_driver_fdctx(dctx,&fdctx);
+	return fdctx.fdin;
+}
+
+static inline int tpax_driver_fdout(const struct tpax_driver_ctx * dctx)
+{
+	struct tpax_fd_ctx fdctx;
+	tpax_get_driver_fdctx(dctx,&fdctx);
+	return fdctx.fdout;
+}
+
+static inline int tpax_driver_fderr(const struct tpax_driver_ctx * dctx)
+{
+	struct tpax_fd_ctx fdctx;
+	tpax_get_driver_fdctx(dctx,&fdctx);
+	return fdctx.fderr;
+}
+
+static inline int tpax_driver_fdlog(const struct tpax_driver_ctx * dctx)
+{
+	struct tpax_fd_ctx fdctx;
+	tpax_get_driver_fdctx(dctx,&fdctx);
+	return fdctx.fdlog;
+}
+
+static inline int tpax_driver_fdcwd(const struct tpax_driver_ctx * dctx)
+{
+	struct tpax_fd_ctx fdctx;
+	tpax_get_driver_fdctx(dctx,&fdctx);
+	return fdctx.fdcwd;
+}
+
+static inline int tpax_driver_fddst(const struct tpax_driver_ctx * dctx)
+{
+	struct tpax_fd_ctx fdctx;
+	tpax_get_driver_fdctx(dctx,&fdctx);
+	return fdctx.fddst;
+}
+
+#endif
diff --git a/src/internal/tpax_errinfo_impl.c b/src/internal/tpax_errinfo_impl.c
new file mode 100644
index 0000000..b610869
--- /dev/null
+++ b/src/internal/tpax_errinfo_impl.c
@@ -0,0 +1,45 @@
+/******************************************************/
+/*  tpax: a topological pax implementation            */
+/*  Copyright (C) 2020  Z. Gilboa                     */
+/*  Released under GPLv2 and GPLv3; see COPYING.TPAX. */
+/******************************************************/
+
+#include <tpax/tpax.h>
+#include "tpax_driver_impl.h"
+#include "tpax_errinfo_impl.h"
+
+int tpax_record_error(
+	const struct tpax_driver_ctx *	dctx,
+	int				esyscode,
+	int				elibcode,
+	const char *			efunction,
+	int				eline,
+	unsigned			eflags,
+	void *				eany)
+{
+	struct tpax_driver_ctx_impl *	ictx;
+	struct tpax_error_info *		erri;
+
+	ictx = tpax_get_driver_ictx(dctx);
+
+	if (ictx->errinfp == ictx->erricap)
+		return -1;
+
+	*ictx->errinfp = &ictx->erribuf[ictx->errinfp - ictx->erriptr];
+	erri = *ictx->errinfp;
+
+	erri->euctx     = ictx->euctx;
+	erri->eunit     = ictx->eunit;
+
+	erri->edctx     = dctx;
+	erri->esyscode  = esyscode;
+	erri->elibcode  = elibcode;
+	erri->efunction = efunction;
+	erri->eline     = eline;
+	erri->eflags    = eflags;
+	erri->eany      = eany;
+
+	ictx->errinfp++;
+
+	return -1;
+}
diff --git a/src/internal/tpax_errinfo_impl.h b/src/internal/tpax_errinfo_impl.h
new file mode 100644
index 0000000..d85d159
--- /dev/null
+++ b/src/internal/tpax_errinfo_impl.h
@@ -0,0 +1,80 @@
+/******************************************************/
+/*  tpax: a topological pax implementation            */
+/*  Copyright (C) 2020  Z. Gilboa                     */
+/*  Released under GPLv2 and GPLv3; see COPYING.TPAX. */
+/******************************************************/
+
+#include <errno.h>
+#include <tpax/tpax.h>
+
+int tpax_record_error(
+	const struct tpax_driver_ctx *,
+	int		esyscode,
+	int		elibcode,
+	const char *	efunction,
+	int		eline,
+	unsigned	eflags,
+	void *		ectx);
+
+#define TPAX_SYSTEM_ERROR(dctx)           \
+	tpax_record_error(                \
+		dctx,                     \
+		errno,                    \
+		0,                        \
+		__func__,                 \
+		__LINE__,                 \
+		TPAX_ERROR_TOP_LEVEL,     \
+		0)
+
+#define TPAX_BUFFER_ERROR(dctx)           \
+	tpax_record_error(                \
+		dctx,                     \
+		ENOBUFS,                  \
+		0,                        \
+		__func__,                 \
+		__LINE__,                 \
+		TPAX_ERROR_TOP_LEVEL,     \
+		0)
+
+#define TPAX_SPAWN_ERROR(dctx)            \
+	tpax_record_error(                \
+		dctx,                     \
+		errno,                    \
+		0,                        \
+		__func__,                 \
+		__LINE__,                 \
+		TPAX_ERROR_TOP_LEVEL      \
+		| (errno ? 0              \
+		   : TPAX_ERROR_CHILD),   \
+		0)
+
+#define TPAX_FILE_ERROR(dctx)             \
+	tpax_record_error(                \
+		dctx,                     \
+		EIO,                      \
+		0,                        \
+		__func__,                 \
+		__LINE__,                 \
+		TPAX_ERROR_TOP_LEVEL,     \
+		0)
+
+#define TPAX_CUSTOM_ERROR(dctx,elibcode)  \
+	tpax_record_error(                \
+		dctx,                     \
+		0,                        \
+		elibcode,                 \
+		__func__,                 \
+		__LINE__,                 \
+		TPAX_ERROR_TOP_LEVEL      \
+		| TPAX_ERROR_CUSTOM,      \
+		0)
+
+#define TPAX_NESTED_ERROR(dctx)           \
+	tpax_record_error(                \
+		dctx,                     \
+		0,                        \
+		0,                        \
+		__func__,                 \
+		__LINE__,                 \
+		TPAX_ERROR_NESTED,        \
+		0)
diff --git a/src/internal/tpax_readlink_impl.h b/src/internal/tpax_readlink_impl.h
new file mode 100644
index 0000000..328b302
--- /dev/null
+++ b/src/internal/tpax_readlink_impl.h
@@ -0,0 +1,31 @@
+/******************************************************/
+/*  tpax: a topological pax implementation            */
+/*  Copyright (C) 2020  Z. Gilboa                     */
+/*  Released under GPLv2 and GPLv3; see COPYING.TPAX. */
+/******************************************************/
+
+#ifndef TPAX_READLINK_IMPL_H
+#define TPAX_READLINK_IMPL_H
+
+#include <unistd.h>
+#include <errno.h>
+
+static inline int tpax_readlink(
+	const char *	restrict path,
+	char *		restrict buf,
+	ssize_t		bufsize)
+{
+	ssize_t ret;
+
+	if ((ret = readlink(path,buf,bufsize)) <= 0) {
+		return -1;
+	} else if (ret == bufsize) {
+		errno = ENOBUFS;
+		return -1;
+	} else {
+		buf[ret] = 0;
+		return 0;
+	}
+}
+
+#endif
diff --git a/src/output/tpax_output_error.c b/src/output/tpax_output_error.c
new file mode 100644
index 0000000..69c4938
--- /dev/null
+++ b/src/output/tpax_output_error.c
@@ -0,0 +1,230 @@
+/******************************************************/
+/*  tpax: a topological pax implementation            */
+/*  Copyright (C) 2020  Z. Gilboa                     */
+/*  Released under GPLv2 and GPLv3; see COPYING.TPAX. */
+/******************************************************/
+
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include <unistd.h>
+#include <tpax/tpax.h>
+
+#include "tpax_driver_impl.h"
+#include "tpax_dprintf_impl.h"
+
+static const char aclr_reset[]   = "\x1b[0m";
+static const char aclr_bold[]    = "\x1b[1m";
+
+static const char aclr_red[]     = "\x1b[31m";
+static const char aclr_green[]   = "\x1b[32m";
+static const char aclr_blue[]    = "\x1b[34m";
+static const char aclr_magenta[] = "\x1b[35m";
+
+static const char * const tpax_error_strings[TPAX_ERR_CAP] = {
+	[TPAX_ERR_FLOW_ERROR]      = "flow error: unexpected condition or other",
+	[TPAX_ERR_FLEE_ERROR]      = "flees and bugs and cats and mice",
+	[TPAX_ERR_NULL_CONTEXT]    = "null driver or unit context",
+	[TPAX_ERR_BAD_DATA]        = "corrupt or wrong daata",
+};
+
+static const char * tpax_output_error_header(const struct tpax_error_info * erri)
+{
+	if (erri->eflags & TPAX_ERROR_CHILD)
+		return "exec error upon";
+
+	else if (erri->eflags & TPAX_ERROR_TOP_LEVEL)
+		return "error logged in";
+
+	else if (erri->eflags & TPAX_ERROR_NESTED)
+		return "< returned to >";
+
+	else
+		return "distorted state";
+}
+
+static const char * tpax_output_unit_header(const struct tpax_error_info * erri)
+{
+	if (!(erri->eflags & TPAX_ERROR_CUSTOM))
+		return "while opening";
+
+	else
+		return "while parsing";
+}
+
+static const char * tpax_output_strerror(
+	const struct tpax_error_info * erri,
+	char (*errbuf)[256])
+{
+	if (erri->eflags & TPAX_ERROR_CUSTOM)
+		return ((erri->elibcode < 0) || (erri->elibcode >= TPAX_ERR_CAP))
+			? "internal error: please report to the maintainer"
+			: tpax_error_strings[erri->elibcode];
+
+	else if (erri->eflags & TPAX_ERROR_NESTED)
+		return "";
+
+	else if (erri->eflags & TPAX_ERROR_CHILD)
+		return "(see child process error messages)";
+
+	else if (erri->esyscode == ENOBUFS)
+		return "input error: string length exceeds buffer size";
+
+	else
+		return strerror_r(erri->esyscode,*errbuf,sizeof(*errbuf))
+			? "internal error: strerror_r(3) call failed"
+			: *errbuf;
+
+}
+
+static int tpax_output_error_record_plain(
+	const struct tpax_driver_ctx *	dctx,
+	const struct tpax_error_info *	erri)
+{
+	const char * epath;
+	char         errbuf[256];
+
+	int          fderr   = tpax_driver_fderr(dctx);
+	const char * errdesc = tpax_output_strerror(erri,&errbuf);
+
+	epath = erri->euctx
+		? *erri->euctx->path
+		: erri->eunit;
+
+	if (epath && !(erri->eflags & TPAX_ERROR_NESTED))
+		if (tpax_dprintf(
+				fderr,
+				"%s: [%s] '%s':\n",
+				dctx->program,
+				tpax_output_unit_header(erri),
+				epath) < 0)
+			return -1;
+
+	if (tpax_dprintf(
+			fderr,
+			"%s: %s %s(), line %d%s%s.\n",
+			dctx->program,
+			tpax_output_error_header(erri),
+			erri->efunction,
+			erri->eline,
+			strlen(errdesc) ? ": " : "",
+			errdesc) < 0)
+		return -1;
+
+	return 0;
+}
+
+static int tpax_output_error_record_annotated(
+	const struct tpax_driver_ctx *	dctx,
+	const struct tpax_error_info *	erri)
+{
+	const char * epath;
+	char         errbuf[256];
+
+	int          fderr   = tpax_driver_fderr(dctx);
+	const char * errdesc = tpax_output_strerror(erri,&errbuf);
+
+	epath = erri->euctx
+		? *erri->euctx->path
+		: erri->eunit;
+
+	if (epath && !(erri->eflags & TPAX_ERROR_NESTED))
+		if (tpax_dprintf(
+				fderr,
+				"%s%s%s:%s %s[%s]%s %s%s'%s'%s:\n",
+
+				aclr_bold,aclr_magenta,
+				dctx->program,
+				aclr_reset,
+
+				aclr_bold,
+				tpax_output_unit_header(erri),
+				aclr_reset,
+
+				aclr_bold,aclr_red,
+				epath,
+				aclr_reset) < 0)
+			return -1;
+
+	if (tpax_dprintf(
+			fderr,
+			"%s%s%s:%s %s%s%s %s%s%s()%s, %s%sline %d%s%s%s%s%s.\n",
+
+			aclr_bold,aclr_magenta,
+			dctx->program,
+			aclr_reset,
+
+			aclr_bold,
+			tpax_output_error_header(erri),
+			aclr_reset,
+
+			aclr_bold,aclr_blue,
+			erri->efunction,
+			aclr_reset,
+
+			aclr_bold,aclr_green,
+			erri->eline,
+			aclr_reset,
+			strlen(errdesc) ? ": " : "",
+
+			aclr_bold,
+			errdesc,
+			aclr_reset) < 0)
+		return -1;
+
+	return 0;
+}
+
+int tpax_output_error_record(
+	const struct tpax_driver_ctx *	dctx,
+	const struct tpax_error_info *	erri)
+{
+	if (dctx->cctx->drvflags & TPAX_DRIVER_ANNOTATE_NEVER)
+		return tpax_output_error_record_plain(dctx,erri);
+
+	else if (dctx->cctx->drvflags & TPAX_DRIVER_ANNOTATE_ALWAYS)
+		return tpax_output_error_record_annotated(dctx,erri);
+
+	else if (isatty(tpax_driver_fderr(dctx)))
+		return tpax_output_error_record_annotated(dctx,erri);
+
+	else
+		return tpax_output_error_record_plain(dctx,erri);
+}
+
+static int tpax_output_error_vector_plain(const struct tpax_driver_ctx * dctx)
+{
+	struct tpax_error_info ** perr;
+
+	for (perr=dctx->errv; *perr; perr++)
+		if (tpax_output_error_record_plain(dctx,*perr))
+			return -1;
+
+	return 0;
+}
+
+static int tpax_output_error_vector_annotated(const struct tpax_driver_ctx * dctx)
+{
+	struct tpax_error_info ** perr;
+
+	for (perr=dctx->errv; *perr; perr++)
+		if (tpax_output_error_record_annotated(dctx,*perr))
+			return -1;
+
+	return 0;
+}
+
+int tpax_output_error_vector(const struct tpax_driver_ctx * dctx)
+{
+	if (dctx->cctx->drvflags & TPAX_DRIVER_ANNOTATE_NEVER)
+		return tpax_output_error_vector_plain(dctx);
+
+	else if (dctx->cctx->drvflags & TPAX_DRIVER_ANNOTATE_ALWAYS)
+		return tpax_output_error_vector_annotated(dctx);
+
+	else if (isatty(tpax_driver_fderr(dctx)))
+		return tpax_output_error_vector_annotated(dctx);
+
+	else
+		return tpax_output_error_vector_plain(dctx);
+}
diff --git a/src/skin/tpax_skin_default.c b/src/skin/tpax_skin_default.c
new file mode 100644
index 0000000..c969ff3
--- /dev/null
+++ b/src/skin/tpax_skin_default.c
@@ -0,0 +1,12 @@
+#include "tpax_driver_impl.h"
+#include "argv/argv.h"
+
+const struct argv_option tpax_default_options[] = {
+	{"version",	0,TAG_VERSION,ARGV_OPTARG_NONE,0,0,0,
+			"show version information"},
+
+	{"help",	0,TAG_HELP,ARGV_OPTARG_OPTIONAL,0,"short|long",0,
+			"show usage information [listing %s options only]"},
+
+	{0,0,0,0,0,0,0,0}
+};
diff --git a/src/tpax.c b/src/tpax.c
new file mode 100644
index 0000000..a2af3b7
--- /dev/null
+++ b/src/tpax.c
@@ -0,0 +1,12 @@
+/******************************************************/
+/*  tpax: a topological pax implementation            */
+/*  Copyright (C) 2020  Z. Gilboa                     */
+/*  Released under GPLv2 and GPLv3; see COPYING.TPAX. */
+/******************************************************/
+
+#include <tpax/tpax.h>
+
+int main(int argc, char ** argv, char ** envp)
+{
+	return tpax_main(argv,envp,0);
+}