zdump: refactor pt_load_add

In an upcoming patch the refactored function `pt_load_add` is reused. While at
it, add a wrap-around check to `pt_load_add`, replace `g.opts.device` access
with `fh->path` (this makes this function easier testable) and improve the
documentation.

Signed-off-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Reviewed-by: Steffen Eiden <seiden@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>

zdump/dfi_elf_common.c

@@ -0,0 +1,61 @@
+/*
+ * zgetdump - Tool for copying and converting System z dumps
+ *
+ * Common ELF core dump input format definitions
+ *
+ * Copyright IBM Corp. 2001, 2022
+ *
+ * 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 "dfi_elf_common.h"
+
+#include <assert.h>
+
+#include "lib/util_log.h"
+
+int pt_load_add(const struct zg_fh *fh, const Elf64_Phdr *phdr, void **data,
+		dfi_mem_chunk_read_fn read_fn, dfi_mem_chunk_free_fn free_fn)
+{
+	assert(fh);
+	assert(phdr);
+	assert(data);
+	assert(read_fn);
+	assert(free_fn);
+
+	util_log_print(
+		UTIL_LOG_DEBUG,
+		"%s p_paddr 0x%016lx p_vaddr 0x%016lx p_offset 0x%016lx p_filesz 0x%016lx p_memsz 0x%016lx\n",
+		__func__, phdr->p_paddr, phdr->p_vaddr, phdr->p_offset, phdr->p_filesz,
+		phdr->p_memsz);
+
+	if (phdr->p_paddr != phdr->p_vaddr) {
+		STDERR("Dump file \"%s\" is a user space core dump\n", fh->path);
+		return -EINVAL;
+	}
+	if (phdr->p_memsz == 0)
+		return -EINVAL;
+	if (phdr->p_offset + phdr->p_filesz > zg_size(fh))
+		return -EINVAL;
+	if (phdr->p_filesz > phdr->p_memsz)
+		return -EINVAL;
+	/* check for wrap-around */
+	if (phdr->p_paddr + phdr->p_filesz < phdr->p_paddr)
+		return -EINVAL;
+
+	if (phdr->p_filesz > 0) {
+		dfi_mem_chunk_add(phdr->p_paddr, phdr->p_filesz, *data, read_fn, free_fn);
+		*data = NULL;
+	} else {
+		/* Free @data directly as it's not used */
+		free_fn(*data);
+		*data = NULL;
+	}
+	if (phdr->p_memsz - phdr->p_filesz > 0) {
+		/* Add zero memory chunk */
+		dfi_mem_chunk_add(phdr->p_paddr + phdr->p_filesz, phdr->p_memsz - phdr->p_filesz,
+				  NULL, dfi_mem_chunk_read_zero, NULL);
+	}
+	return 0;
+}