Adding upstream version 115.7.0esr.upstream/115.7.0esr

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 921 insertions, 0 deletions

diff --git a/third_party/rust/glslopt/glsl-optimizer/src/util/ralloc.c b/third_party/rust/glslopt/glsl-optimizer/src/util/ralloc.c
new file mode 100644
index 0000000000..7b7b018558
--- /dev/null
+++ b/third_party/rust/glslopt/glsl-optimizer/src/util/ralloc.c
@@ -0,0 +1,921 @@
+/*
+ * Copyright © 2010 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#include <assert.h>
+#include <stdlib.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdint.h>
+
+/* Some versions of MinGW are missing _vscprintf's declaration, although they
+ * still provide the symbol in the import library. */
+#ifdef __MINGW32__
+_CRTIMP int _vscprintf(const char *format, va_list argptr);
+#endif
+
+#include "ralloc.h"
+
+#ifndef va_copy
+#ifdef __va_copy
+#define va_copy(dest, src) __va_copy((dest), (src))
+#else
+#define va_copy(dest, src) (dest) = (src)
+#endif
+#endif
+
+#define CANARY 0x5A1106
+
+/* Align the header's size so that ralloc() allocations will return with the
+ * same alignment as a libc malloc would have (8 on 32-bit GLIBC, 16 on
+ * 64-bit), avoiding performance penalities on x86 and alignment faults on
+ * ARM.
+ */
+struct
+#ifdef _MSC_VER
+#if _WIN64
+__declspec(align(16))
+#else
+ __declspec(align(8))
+#endif
+#elif defined(__LP64__)
+ __attribute__((aligned(16)))
+#else
+ __attribute__((aligned(8)))
+#endif
+   ralloc_header
+{
+#ifndef NDEBUG
+   /* A canary value used to determine whether a pointer is ralloc'd. */
+   unsigned canary;
+#endif
+
+   struct ralloc_header *parent;
+
+   /* The first child (head of a linked list) */
+   struct ralloc_header *child;
+
+   /* Linked list of siblings */
+   struct ralloc_header *prev;
+   struct ralloc_header *next;
+
+   void (*destructor)(void *);
+};
+
+typedef struct ralloc_header ralloc_header;
+
+static void unlink_block(ralloc_header *info);
+static void unsafe_free(ralloc_header *info);
+
+static ralloc_header *
+get_header(const void *ptr)
+{
+   ralloc_header *info = (ralloc_header *) (((char *) ptr) -
+					    sizeof(ralloc_header));
+   assert(info->canary == CANARY);
+   return info;
+}
+
+#define PTR_FROM_HEADER(info) (((char *) info) + sizeof(ralloc_header))
+
+static void
+add_child(ralloc_header *parent, ralloc_header *info)
+{
+   if (parent != NULL) {
+      info->parent = parent;
+      info->next = parent->child;
+      parent->child = info;
+
+      if (info->next != NULL)
+	 info->next->prev = info;
+   }
+}
+
+void *
+ralloc_context(const void *ctx)
+{
+   return ralloc_size(ctx, 0);
+}
+
+void *
+ralloc_size(const void *ctx, size_t size)
+{
+   void *block = malloc(size + sizeof(ralloc_header));
+   ralloc_header *info;
+   ralloc_header *parent;
+
+   if (unlikely(block == NULL))
+      return NULL;
+
+   info = (ralloc_header *) block;
+   /* measurements have shown that calloc is slower (because of
+    * the multiplication overflow checking?), so clear things
+    * manually
+    */
+   info->parent = NULL;
+   info->child = NULL;
+   info->prev = NULL;
+   info->next = NULL;
+   info->destructor = NULL;
+
+   parent = ctx != NULL ? get_header(ctx) : NULL;
+
+   add_child(parent, info);
+
+#ifndef NDEBUG
+   info->canary = CANARY;
+#endif
+
+   return PTR_FROM_HEADER(info);
+}
+
+void *
+rzalloc_size(const void *ctx, size_t size)
+{
+   void *ptr = ralloc_size(ctx, size);
+
+   if (likely(ptr))
+      memset(ptr, 0, size);
+
+   return ptr;
+}
+
+/* helper function - assumes ptr != NULL */
+static void *
+resize(void *ptr, size_t size)
+{
+   ralloc_header *child, *old, *info;
+
+   old = get_header(ptr);
+   info = realloc(old, size + sizeof(ralloc_header));
+
+   if (info == NULL)
+      return NULL;
+
+   /* Update parent and sibling's links to the reallocated node. */
+   if (info != old && info->parent != NULL) {
+      if (info->parent->child == old)
+	 info->parent->child = info;
+
+      if (info->prev != NULL)
+	 info->prev->next = info;
+
+      if (info->next != NULL)
+	 info->next->prev = info;
+   }
+
+   /* Update child->parent links for all children */
+   for (child = info->child; child != NULL; child = child->next)
+      child->parent = info;
+
+   return PTR_FROM_HEADER(info);
+}
+
+void *
+reralloc_size(const void *ctx, void *ptr, size_t size)
+{
+   if (unlikely(ptr == NULL))
+      return ralloc_size(ctx, size);
+
+   assert(ralloc_parent(ptr) == ctx);
+   return resize(ptr, size);
+}
+
+void *
+rerzalloc_size(const void *ctx, void *ptr, size_t old_size, size_t new_size)
+{
+   if (unlikely(ptr == NULL))
+      return rzalloc_size(ctx, new_size);
+
+   assert(ralloc_parent(ptr) == ctx);
+   ptr = resize(ptr, new_size);
+
+   if (new_size > old_size)
+      memset((char *)ptr + old_size, 0, new_size - old_size);
+
+   return ptr;
+}
+
+void *
+ralloc_array_size(const void *ctx, size_t size, unsigned count)
+{
+   if (count > SIZE_MAX/size)
+      return NULL;
+
+   return ralloc_size(ctx, size * count);
+}
+
+void *
+rzalloc_array_size(const void *ctx, size_t size, unsigned count)
+{
+   if (count > SIZE_MAX/size)
+      return NULL;
+
+   return rzalloc_size(ctx, size * count);
+}
+
+void *
+reralloc_array_size(const void *ctx, void *ptr, size_t size, unsigned count)
+{
+   if (count > SIZE_MAX/size)
+      return NULL;
+
+   return reralloc_size(ctx, ptr, size * count);
+}
+
+void *
+rerzalloc_array_size(const void *ctx, void *ptr, size_t size,
+                     unsigned old_count, unsigned new_count)
+{
+   if (new_count > SIZE_MAX/size)
+      return NULL;
+
+   return rerzalloc_size(ctx, ptr, size * old_count, size * new_count);
+}
+
+void
+ralloc_free(void *ptr)
+{
+   ralloc_header *info;
+
+   if (ptr == NULL)
+      return;
+
+   info = get_header(ptr);
+   unlink_block(info);
+   unsafe_free(info);
+}
+
+static void
+unlink_block(ralloc_header *info)
+{
+   /* Unlink from parent & siblings */
+   if (info->parent != NULL) {
+      if (info->parent->child == info)
+	 info->parent->child = info->next;
+
+      if (info->prev != NULL)
+	 info->prev->next = info->next;
+
+      if (info->next != NULL)
+	 info->next->prev = info->prev;
+   }
+   info->parent = NULL;
+   info->prev = NULL;
+   info->next = NULL;
+}
+
+static void
+unsafe_free(ralloc_header *info)
+{
+   /* Recursively free any children...don't waste time unlinking them. */
+   ralloc_header *temp;
+   while (info->child != NULL) {
+      temp = info->child;
+      info->child = temp->next;
+      unsafe_free(temp);
+   }
+
+   /* Free the block itself.  Call the destructor first, if any. */
+   if (info->destructor != NULL)
+      info->destructor(PTR_FROM_HEADER(info));
+
+   free(info);
+}
+
+void
+ralloc_steal(const void *new_ctx, void *ptr)
+{
+   ralloc_header *info, *parent;
+
+   if (unlikely(ptr == NULL))
+      return;
+
+   info = get_header(ptr);
+   parent = new_ctx ? get_header(new_ctx) : NULL;
+
+   unlink_block(info);
+
+   add_child(parent, info);
+}
+
+void
+ralloc_adopt(const void *new_ctx, void *old_ctx)
+{
+   ralloc_header *new_info, *old_info, *child;
+
+   if (unlikely(old_ctx == NULL))
+      return;
+
+   old_info = get_header(old_ctx);
+   new_info = get_header(new_ctx);
+
+   /* If there are no children, bail. */
+   if (unlikely(old_info->child == NULL))
+      return;
+
+   /* Set all the children's parent to new_ctx; get a pointer to the last child. */
+   for (child = old_info->child; child->next != NULL; child = child->next) {
+      child->parent = new_info;
+   }
+   child->parent = new_info;
+
+   /* Connect the two lists together; parent them to new_ctx; make old_ctx empty. */
+   child->next = new_info->child;
+   if (child->next)
+      child->next->prev = child;
+   new_info->child = old_info->child;
+   old_info->child = NULL;
+}
+
+void *
+ralloc_parent(const void *ptr)
+{
+   ralloc_header *info;
+
+   if (unlikely(ptr == NULL))
+      return NULL;
+
+   info = get_header(ptr);
+   return info->parent ? PTR_FROM_HEADER(info->parent) : NULL;
+}
+
+void
+ralloc_set_destructor(const void *ptr, void(*destructor)(void *))
+{
+   ralloc_header *info = get_header(ptr);
+   info->destructor = destructor;
+}
+
+char *
+ralloc_strdup(const void *ctx, const char *str)
+{
+   size_t n;
+   char *ptr;
+
+   if (unlikely(str == NULL))
+      return NULL;
+
+   n = strlen(str);
+   ptr = ralloc_array(ctx, char, n + 1);
+   memcpy(ptr, str, n);
+   ptr[n] = '\0';
+   return ptr;
+}
+
+char *
+ralloc_strndup(const void *ctx, const char *str, size_t max)
+{
+   size_t n;
+   char *ptr;
+
+   if (unlikely(str == NULL))
+      return NULL;
+
+   n = strnlen(str, max);
+   ptr = ralloc_array(ctx, char, n + 1);
+   memcpy(ptr, str, n);
+   ptr[n] = '\0';
+   return ptr;
+}
+
+/* helper routine for strcat/strncat - n is the exact amount to copy */
+static bool
+cat(char **dest, const char *str, size_t n)
+{
+   char *both;
+   size_t existing_length;
+   assert(dest != NULL && *dest != NULL);
+
+   existing_length = strlen(*dest);
+   both = resize(*dest, existing_length + n + 1);
+   if (unlikely(both == NULL))
+      return false;
+
+   memcpy(both + existing_length, str, n);
+   both[existing_length + n] = '\0';
+
+   *dest = both;
+   return true;
+}
+
+
+bool
+ralloc_strcat(char **dest, const char *str)
+{
+   return cat(dest, str, strlen(str));
+}
+
+bool
+ralloc_strncat(char **dest, const char *str, size_t n)
+{
+   return cat(dest, str, strnlen(str, n));
+}
+
+bool
+ralloc_str_append(char **dest, const char *str,
+                  size_t existing_length, size_t str_size)
+{
+   char *both;
+   assert(dest != NULL && *dest != NULL);
+
+   both = resize(*dest, existing_length + str_size + 1);
+   if (unlikely(both == NULL))
+      return false;
+
+   memcpy(both + existing_length, str, str_size);
+   both[existing_length + str_size] = '\0';
+
+   *dest = both;
+
+   return true;
+}
+
+char *
+ralloc_asprintf(const void *ctx, const char *fmt, ...)
+{
+   char *ptr;
+   va_list args;
+   va_start(args, fmt);
+   ptr = ralloc_vasprintf(ctx, fmt, args);
+   va_end(args);
+   return ptr;
+}
+
+size_t
+printf_length(const char *fmt, va_list untouched_args)
+{
+   int size;
+   char junk;
+
+   /* Make a copy of the va_list so the original caller can still use it */
+   va_list args;
+   va_copy(args, untouched_args);
+
+#ifdef _WIN32
+   /* We need to use _vcsprintf to calculate the size as vsnprintf returns -1
+    * if the number of characters to write is greater than count.
+    */
+   size = _vscprintf(fmt, args);
+   (void)junk;
+#else
+   size = vsnprintf(&junk, 1, fmt, args);
+#endif
+   assert(size >= 0);
+
+   va_end(args);
+
+   return size;
+}
+
+char *
+ralloc_vasprintf(const void *ctx, const char *fmt, va_list args)
+{
+   size_t size = printf_length(fmt, args) + 1;
+
+   char *ptr = ralloc_size(ctx, size);
+   if (ptr != NULL)
+      vsnprintf(ptr, size, fmt, args);
+
+   return ptr;
+}
+
+bool
+ralloc_asprintf_append(char **str, const char *fmt, ...)
+{
+   bool success;
+   va_list args;
+   va_start(args, fmt);
+   success = ralloc_vasprintf_append(str, fmt, args);
+   va_end(args);
+   return success;
+}
+
+bool
+ralloc_vasprintf_append(char **str, const char *fmt, va_list args)
+{
+   size_t existing_length;
+   assert(str != NULL);
+   existing_length = *str ? strlen(*str) : 0;
+   return ralloc_vasprintf_rewrite_tail(str, &existing_length, fmt, args);
+}
+
+bool
+ralloc_asprintf_rewrite_tail(char **str, size_t *start, const char *fmt, ...)
+{
+   bool success;
+   va_list args;
+   va_start(args, fmt);
+   success = ralloc_vasprintf_rewrite_tail(str, start, fmt, args);
+   va_end(args);
+   return success;
+}
+
+bool
+ralloc_vasprintf_rewrite_tail(char **str, size_t *start, const char *fmt,
+			      va_list args)
+{
+   size_t new_length;
+   char *ptr;
+
+   assert(str != NULL);
+
+   if (unlikely(*str == NULL)) {
+      // Assuming a NULL context is probably bad, but it's expected behavior.
+      *str = ralloc_vasprintf(NULL, fmt, args);
+      *start = strlen(*str);
+      return true;
+   }
+
+   new_length = printf_length(fmt, args);
+
+   ptr = resize(*str, *start + new_length + 1);
+   if (unlikely(ptr == NULL))
+      return false;
+
+   vsnprintf(ptr + *start, new_length + 1, fmt, args);
+   *str = ptr;
+   *start += new_length;
+   return true;
+}
+
+/***************************************************************************
+ * Linear allocator for short-lived allocations.
+ ***************************************************************************
+ *
+ * The allocator consists of a parent node (2K buffer), which requires
+ * a ralloc parent, and child nodes (allocations). Child nodes can't be freed
+ * directly, because the parent doesn't track them. You have to release
+ * the parent node in order to release all its children.
+ *
+ * The allocator uses a fixed-sized buffer with a monotonically increasing
+ * offset after each allocation. If the buffer is all used, another buffer
+ * is allocated, sharing the same ralloc parent, so all buffers are at
+ * the same level in the ralloc hierarchy.
+ *
+ * The linear parent node is always the first buffer and keeps track of all
+ * other buffers.
+ */
+
+#define MIN_LINEAR_BUFSIZE 2048
+#define SUBALLOC_ALIGNMENT 8
+#define LMAGIC 0x87b9c7d3
+
+struct
+#ifdef _MSC_VER
+ __declspec(align(8))
+#elif defined(__LP64__)
+ __attribute__((aligned(16)))
+#else
+ __attribute__((aligned(8)))
+#endif
+   linear_header {
+#ifndef NDEBUG
+   unsigned magic;   /* for debugging */
+#endif
+   unsigned offset;  /* points to the first unused byte in the buffer */
+   unsigned size;    /* size of the buffer */
+   void *ralloc_parent;          /* new buffers will use this */
+   struct linear_header *next;   /* next buffer if we have more */
+   struct linear_header *latest; /* the only buffer that has free space */
+
+   /* After this structure, the buffer begins.
+    * Each suballocation consists of linear_size_chunk as its header followed
+    * by the suballocation, so it goes:
+    *
+    * - linear_size_chunk
+    * - allocated space
+    * - linear_size_chunk
+    * - allocated space
+    * etc.
+    *
+    * linear_size_chunk is only needed by linear_realloc.
+    */
+};
+
+struct linear_size_chunk {
+   unsigned size; /* for realloc */
+   unsigned _padding;
+};
+
+typedef struct linear_header linear_header;
+typedef struct linear_size_chunk linear_size_chunk;
+
+#define LINEAR_PARENT_TO_HEADER(parent) \
+   (linear_header*) \
+   ((char*)(parent) - sizeof(linear_size_chunk) - sizeof(linear_header))
+
+/* Allocate the linear buffer with its header. */
+static linear_header *
+create_linear_node(void *ralloc_ctx, unsigned min_size)
+{
+   linear_header *node;
+
+   min_size += sizeof(linear_size_chunk);
+
+   if (likely(min_size < MIN_LINEAR_BUFSIZE))
+      min_size = MIN_LINEAR_BUFSIZE;
+
+   node = ralloc_size(ralloc_ctx, sizeof(linear_header) + min_size);
+   if (unlikely(!node))
+      return NULL;
+
+#ifndef NDEBUG
+   node->magic = LMAGIC;
+#endif
+   node->offset = 0;
+   node->size = min_size;
+   node->ralloc_parent = ralloc_ctx;
+   node->next = NULL;
+   node->latest = node;
+   return node;
+}
+
+void *
+linear_alloc_child(void *parent, unsigned size)
+{
+   linear_header *first = LINEAR_PARENT_TO_HEADER(parent);
+   linear_header *latest = first->latest;
+   linear_header *new_node;
+   linear_size_chunk *ptr;
+   unsigned full_size;
+
+   assert(first->magic == LMAGIC);
+   assert(!latest->next);
+
+   size = ALIGN_POT(size, SUBALLOC_ALIGNMENT);
+   full_size = sizeof(linear_size_chunk) + size;
+
+   if (unlikely(latest->offset + full_size > latest->size)) {
+      /* allocate a new node */
+      new_node = create_linear_node(latest->ralloc_parent, size);
+      if (unlikely(!new_node))
+         return NULL;
+
+      first->latest = new_node;
+      latest->latest = new_node;
+      latest->next = new_node;
+      latest = new_node;
+   }
+
+   ptr = (linear_size_chunk *)((char*)&latest[1] + latest->offset);
+   ptr->size = size;
+   latest->offset += full_size;
+
+   assert((uintptr_t)&ptr[1] % SUBALLOC_ALIGNMENT == 0);
+   return &ptr[1];
+}
+
+void *
+linear_alloc_parent(void *ralloc_ctx, unsigned size)
+{
+   linear_header *node;
+
+   if (unlikely(!ralloc_ctx))
+      return NULL;
+
+   size = ALIGN_POT(size, SUBALLOC_ALIGNMENT);
+
+   node = create_linear_node(ralloc_ctx, size);
+   if (unlikely(!node))
+      return NULL;
+
+   return linear_alloc_child((char*)node +
+                             sizeof(linear_header) +
+                             sizeof(linear_size_chunk), size);
+}
+
+void *
+linear_zalloc_child(void *parent, unsigned size)
+{
+   void *ptr = linear_alloc_child(parent, size);
+
+   if (likely(ptr))
+      memset(ptr, 0, size);
+   return ptr;
+}
+
+void *
+linear_zalloc_parent(void *parent, unsigned size)
+{
+   void *ptr = linear_alloc_parent(parent, size);
+
+   if (likely(ptr))
+      memset(ptr, 0, size);
+   return ptr;
+}
+
+void
+linear_free_parent(void *ptr)
+{
+   linear_header *node;
+
+   if (unlikely(!ptr))
+      return;
+
+   node = LINEAR_PARENT_TO_HEADER(ptr);
+   assert(node->magic == LMAGIC);
+
+   while (node) {
+      void *ptr = node;
+
+      node = node->next;
+      ralloc_free(ptr);
+   }
+}
+
+void
+ralloc_steal_linear_parent(void *new_ralloc_ctx, void *ptr)
+{
+   linear_header *node;
+
+   if (unlikely(!ptr))
+      return;
+
+   node = LINEAR_PARENT_TO_HEADER(ptr);
+   assert(node->magic == LMAGIC);
+
+   while (node) {
+      ralloc_steal(new_ralloc_ctx, node);
+      node->ralloc_parent = new_ralloc_ctx;
+      node = node->next;
+   }
+}
+
+void *
+ralloc_parent_of_linear_parent(void *ptr)
+{
+   linear_header *node = LINEAR_PARENT_TO_HEADER(ptr);
+   assert(node->magic == LMAGIC);
+   return node->ralloc_parent;
+}
+
+void *
+linear_realloc(void *parent, void *old, unsigned new_size)
+{
+   unsigned old_size = 0;
+   ralloc_header *new_ptr;
+
+   new_ptr = linear_alloc_child(parent, new_size);
+
+   if (unlikely(!old))
+      return new_ptr;
+
+   old_size = ((linear_size_chunk*)old)[-1].size;
+
+   if (likely(new_ptr && old_size))
+      memcpy(new_ptr, old, MIN2(old_size, new_size));
+
+   return new_ptr;
+}
+
+/* All code below is pretty much copied from ralloc and only the alloc
+ * calls are different.
+ */
+
+char *
+linear_strdup(void *parent, const char *str)
+{
+   unsigned n;
+   char *ptr;
+
+   if (unlikely(!str))
+      return NULL;
+
+   n = strlen(str);
+   ptr = linear_alloc_child(parent, n + 1);
+   if (unlikely(!ptr))
+      return NULL;
+
+   memcpy(ptr, str, n);
+   ptr[n] = '\0';
+   return ptr;
+}
+
+char *
+linear_asprintf(void *parent, const char *fmt, ...)
+{
+   char *ptr;
+   va_list args;
+   va_start(args, fmt);
+   ptr = linear_vasprintf(parent, fmt, args);
+   va_end(args);
+   return ptr;
+}
+
+char *
+linear_vasprintf(void *parent, const char *fmt, va_list args)
+{
+   unsigned size = printf_length(fmt, args) + 1;
+
+   char *ptr = linear_alloc_child(parent, size);
+   if (ptr != NULL)
+      vsnprintf(ptr, size, fmt, args);
+
+   return ptr;
+}
+
+bool
+linear_asprintf_append(void *parent, char **str, const char *fmt, ...)
+{
+   bool success;
+   va_list args;
+   va_start(args, fmt);
+   success = linear_vasprintf_append(parent, str, fmt, args);
+   va_end(args);
+   return success;
+}
+
+bool
+linear_vasprintf_append(void *parent, char **str, const char *fmt, va_list args)
+{
+   size_t existing_length;
+   assert(str != NULL);
+   existing_length = *str ? strlen(*str) : 0;
+   return linear_vasprintf_rewrite_tail(parent, str, &existing_length, fmt, args);
+}
+
+bool
+linear_asprintf_rewrite_tail(void *parent, char **str, size_t *start,
+                             const char *fmt, ...)
+{
+   bool success;
+   va_list args;
+   va_start(args, fmt);
+   success = linear_vasprintf_rewrite_tail(parent, str, start, fmt, args);
+   va_end(args);
+   return success;
+}
+
+bool
+linear_vasprintf_rewrite_tail(void *parent, char **str, size_t *start,
+                              const char *fmt, va_list args)
+{
+   size_t new_length;
+   char *ptr;
+
+   assert(str != NULL);
+
+   if (unlikely(*str == NULL)) {
+      *str = linear_vasprintf(parent, fmt, args);
+      *start = strlen(*str);
+      return true;
+   }
+
+   new_length = printf_length(fmt, args);
+
+   ptr = linear_realloc(parent, *str, *start + new_length + 1);
+   if (unlikely(ptr == NULL))
+      return false;
+
+   vsnprintf(ptr + *start, new_length + 1, fmt, args);
+   *str = ptr;
+   *start += new_length;
+   return true;
+}
+
+/* helper routine for strcat/strncat - n is the exact amount to copy */
+static bool
+linear_cat(void *parent, char **dest, const char *str, unsigned n)
+{
+   char *both;
+   unsigned existing_length;
+   assert(dest != NULL && *dest != NULL);
+
+   existing_length = strlen(*dest);
+   both = linear_realloc(parent, *dest, existing_length + n + 1);
+   if (unlikely(both == NULL))
+      return false;
+
+   memcpy(both + existing_length, str, n);
+   both[existing_length + n] = '\0';
+
+   *dest = both;
+   return true;
+}
+
+bool
+linear_strcat(void *parent, char **dest, const char *str)
+{
+   return linear_cat(parent, dest, str, strlen(str));
+}